React Nativeで広告ライブラリadmobのビルドに失敗する

前提・実現したいこと

React Nativeでスマートフォンアプリ開発を行なっております。
広告ライブラリのreact-native-admob-native-adsで広告を表示させる機能を実装中です。
react-native-admob-native-adsの設定をAndroidの設定手順に沿って実施しました。
設定後、npx react-native run-androidでAndroidアプリを起動すると、以下のビルドエラーが出ており、解決ができません。

発生している問題・エラーメッセージ

FAILURE: Build completed with 2 failures.

1: Task failed with an exception.
-----------
* Where:
Build file '/Users/xxx.yyy/project/react-native-tutorial/node_modules/react-native-admob-native-ads/android/build.gradle' line: 31

* What went wrong:
A problem occurred evaluating project ':react-native-admob-native-ads'.
> Plugin with id 'maven' not found.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
==============================================================================

2: Task failed with an exception.
-----------
* What went wrong:
A problem occurred configuring project ':react-native-admob-native-ads'.
> com.android.builder.errors.EvalIssueException: compileSdkVersion is not specified. Please add it to build.gradle

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
==============================================================================

* Get more help at https://help.gradle.org

BUILD FAILED in 7s

    at makeError (/Users/xxx.yyy/project/react-native-tutorial/node_modules/execa/index.js:174:9)
    at /Users/xxx.yyy/project/react-native-tutorial/node_modules/execa/index.js:278:16
    at processTicksAndRejections (node:internal/process/task_queues:96:5)
    at async runOnAllDevices (/Users/txxx.yyy/project/react-native-tutorial/node_modules/@react-native-community/cli-platform-android/build/commands/runAndroid/runOnAllDevices.js:109:5)
    at async Command.handleAction (/Users/xxx.yyy/project/react-native-tutorial/node_modules/@react-native-community/cli/build/index.js:192:9)

該当のソースコード

androidフォルダ配下のandroid/build.gradleは以下です。

gradle
1// Top-level build file where you can add configuration options common to all sub-projects/modules.
2
3buildscript {
4    ext {
5        buildToolsVersion = "30.0.2"
6        minSdkVersion = 21
7        compileSdkVersion = 30
8        targetSdkVersion = 30
9        ndkVersion = "21.4.7075529"
10    }
11    repositories {
12        google()
13        mavenCentral()
14    }
15    dependencies {
16        classpath("com.android.tools.build:gradle:4.2.2")
17        // NOTE: Do not place your application dependencies here; they belong
18        // in the individual module build.gradle files
19    }
20}
21
22allprojects {
23    repositories {
24        maven {
25            // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
26            url("$rootDir/../node_modules/react-native/android")
27        }
28        maven {
29            // Android JSC is installed from npm
30            url("$rootDir/../node_modules/jsc-android/dist")
31        }
32        mavenCentral {
33            // We don't want to fetch react-native from Maven Central as there are
34            // older versions over there.
35            content {
36                excludeGroup "com.facebook.react"
37            }
38        }
39        google()
40        mavenCentral() // ☆追加
41        maven { url 'https://www.jitpack.io' }
42        jcenter() {
43            content {
44                includeModule("com.yqritc", "android-scalablevideoview")
45            }
46        }
47    }
48}

appフォルダ配下のbuild.gradleは以下です。

gradle
1apply plugin: "com.android.application"
2
3import com.android.build.OutputFile
4
5project.ext.react = [
6    enableHermes: false,  // clean and rebuild if changing
7]
8
9apply from: "../../node_modules/react-native/react.gradle"
10
11def enableSeparateBuildPerCPUArchitecture = false
12
13def enableProguardInReleaseBuilds = false
14
15def jscFlavor = 'org.webkit:android-jsc:+'
16
17def enableHermes = project.ext.react.get("enableHermes", false);
18
19def nativeArchitectures = project.getProperties().get("reactNativeDebugArchitectures")
20
21android {
22    ndkVersion rootProject.ext.ndkVersion
23
24    compileSdkVersion rootProject.ext.compileSdkVersion
25
26    defaultConfig {
27        applicationId "com.awesomeproject"
28        minSdkVersion rootProject.ext.minSdkVersion
29        targetSdkVersion rootProject.ext.targetSdkVersion
30        versionCode 1
31        versionName "1.0"
32    }
33    splits {
34        abi {
35            reset()
36            enable enableSeparateBuildPerCPUArchitecture
37            universalApk false  // If true, also generate a universal APK
38            include "armeabi-v7a", "x86", "arm64-v8a", "x86_64"
39        }
40    }
41    signingConfigs {
42        debug {
43            storeFile file('debug.keystore')
44            storePassword 'android'
45            keyAlias 'androiddebugkey'
46            keyPassword 'android'
47        }
48    }
49    buildTypes {
50        debug {
51            signingConfig signingConfigs.debug
52            if (nativeArchitectures) {
53                ndk {
54                    abiFilters nativeArchitectures.split(',')
55                }
56            }
57        }
58        release {
59            // Caution! In production, you need to generate your own keystore file.
60            // see https://reactnative.dev/docs/signed-apk-android.
61            signingConfig signingConfigs.debug
62            minifyEnabled enableProguardInReleaseBuilds
63            proguardFiles getDefaultProguardFile("proguard-android.txt"), "proguard-rules.pro"
64        }
65    }
66
67    // applicationVariants are e.g. debug, release
68    applicationVariants.all { variant ->
69        variant.outputs.each { output ->
70            // For each separate APK per architecture, set a unique version code as described here:
71            // https://developer.android.com/studio/build/configure-apk-splits.html
72            // Example: versionCode 1 will generate 1001 for armeabi-v7a, 1002 for x86, etc.
73            def versionCodes = ["armeabi-v7a": 1, "x86": 2, "arm64-v8a": 3, "x86_64": 4]
74            def abi = output.getFilter(OutputFile.ABI)
75            if (abi != null) {  // null for the universal-debug, universal-release variants
76                output.versionCodeOverride =
77                        defaultConfig.versionCode * 1000 + versionCodes.get(abi)
78            }
79
80        }
81    }
82}
83
84dependencies {
85    implementation fileTree(dir: "libs", include: ["*.jar"])
86    //noinspection GradleDynamicVersion
87    implementation "com.facebook.react:react-native:+"  // From node_modules
88
89    implementation "androidx.swiperefreshlayout:swiperefreshlayout:1.0.0"
90
91    implementation 'com.google.android.gms:play-services-ads:20.5.0'
92
93    debugImplementation("com.facebook.flipper:flipper:${FLIPPER_VERSION}") {
94        exclude group:'com.facebook.fbjni'
95    }
96
97    debugImplementation("com.facebook.flipper:flipper-network-plugin:${FLIPPER_VERSION}") {
98        exclude group:'com.facebook.flipper'
99        exclude group:'com.squareup.okhttp3', module:'okhttp'
100    }
101
102    debugImplementation("com.facebook.flipper:flipper-fresco-plugin:${FLIPPER_VERSION}") {
103        exclude group:'com.facebook.flipper'
104    }
105
106    if (enableHermes) {
107        def hermesPath = "../../node_modules/hermes-engine/android/";
108        debugImplementation files(hermesPath + "hermes-debug.aar")
109        releaseImplementation files(hermesPath + "hermes-release.aar")
110    } else {
111        implementation jscFlavor
112    }
113}
114
115// Run this once to be able to run the application with BUCK
116// puts all compile dependencies into folder libs for BUCK to use
117task copyDownloadableDepsToLibs(type: Copy) {
118    from configurations.implementation
119    into 'libs'
120}
121
122apply from: file("../../node_modules/@react-native-community/cli-platform-android/native_modules.gradle"); applyNativeModulesAppBuildGradle(project)

AndroidManifest.xmlは以下です。

xml
1<manifest xmlns:android="http://schemas.android.com/apk/res/android"
2  package="com.awesomeproject">
3
4    <uses-permission android:name="android.permission.INTERNET" />
5
6    <application
7      android:name=".MainApplication"
8      android:label="@string/app_name"
9      android:icon="@mipmap/ic_launcher"
10      android:roundIcon="@mipmap/ic_launcher_round"
11      android:allowBackup="false"
12      android:theme="@style/AppTheme">
13        <meta-data
14          android:name="com.google.android.gms.ads.APPLICATION_ID" // ☆追加
15          android:value="ca-app-pub-xxxxxxxxx-yyyyyyyyy"/> // ☆追加
16
17      <activity
18        android:name=".MainActivity"
19        android:label="@string/app_name"
20        android:configChanges="keyboard|keyboardHidden|orientation|screenSize|uiMode"
21        android:launchMode="singleTask"
22        android:screenOrientation="portrait"
23        android:windowSoftInputMode="adjustResize">
24        <intent-filter>
25            <action android:name="android.intent.action.MAIN" />
26            <category android:name="android.intent.category.LAUNCHER" />
27        </intent-filter>
28      </activity>
29    </application>
30</manifest>

試したこと

compileSdkVersion is not specified. Please add it to build.gradleのエラーが出ていたので、gradleファイルにcompileSdkVersionが定義されているかを確認しました。上記のソースにある通り定義されていました。
ネットで検索しましたが、有益な解決方法がありませんでした。