python kivy　エラーメッセージの意味がわかりません。

kivyの公式サイトを見ながらkivyをインストールしたのですが、
以下のエラー？メッセージが出てきてデスクトップアプリができません。

発生している問題・エラーメッセージ

[Running] python -u "/Users/＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊＊/Kivy _file.py"
[INFO   ] [Logger      ] Record log in /＊＊＊＊＊＊＊＊/.kivy/logs/kivy_21-01-22_12.txt
[INFO   ] [Kivy        ] v2.1.0.dev0
[INFO   ] [Kivy        ] Installed at "/opt/＊＊/python3.8/site-packages/kivy/__init__.py"
[INFO   ] [Python      ] v3.8.3 (default, Jul  2 2020, 11:26:31) 
[Clang 10.0.0 ]
[INFO   ] [Python      ] Interpreter at "/opt/anaconda3/bin/python"
[INFO   ] [Logger      ] Purge log fired. Processing...
[INFO   ] [Logger      ] Purge finished!
[INFO   ] [Factory     ] 187 symbols loaded
[INFO   ] [Image       ] Providers: img_tex, img_imageio, img_dds, img_sdl2, img_pil (img_ffpyplayer ignored)
[INFO   ] [Text        ] Provider: sdl2
[INFO   ] [Window      ] Provider: sdl2
[CRITICAL] [App         ] Unable to get a Window, abort.

[Done] exited with code=1 in 0.47 seconds

該当のソースコード

python
1import kivy
2
3from kivy.app import App
4from kivy.uix.button import Label
5
6
7class sample(App):
8    def build(self):
9        return Label(text = "Hello YouTube")
10
11if __name__ == "__main__":
12    sample().run()