ffmpegがダウンロードできません助けてください

brew install ffmpeg

とMacターミナルでHomeBrewをダウンロードした後ffmpegをインストールしようとしたら

Error: Could not symlink share/doc/libsndfile/FAQ.html
Target /usr/local/share/doc/libsndfile/FAQ.html
is a symlink belonging to libsndfile. You can unlink it:
brew unlink libsndfile

To force the link and overwrite all conflicting files:
brew link --overwrite libsndfile

To list all files that would be deleted:
brew link --overwrite --dry-run libsndfile

と表示されインストールができません。そこで色々調べたところ

brew doctor

で何が原因か表示させたのですが、そこから知識不足で読み取れず困っています。
brew doctorの結果が長くなりますがこれ↓です。

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: A newer Command Line Tools release is available.
Update them from Software Update in System Preferences or run:
softwareupdate --all --install --force

If that doesn't show you any updates, run:
sudo rm -rf /Library/Developer/CommandLineTools
sudo xcode-select --install

Alternatively, manually download them from:
https://developer.apple.com/download/more/.
You should download the Command Line Tools for Xcode 12.5.

Warning: gettext files detected at a system prefix.
These files can cause compilation and link failures, especially if they
are compiled with improper architectures. Consider removing these files:
/usr/local/lib/libgettextlib.dylib
/usr/local/lib/libintl.dylib
/usr/local/include/libintl.h
/usr/local/lib/libgettextlib.dylib
/usr/local/lib/libintl.dylib
/usr/local/include/libintl.h

Warning: You have unlinked kegs in your Cellar.
Leaving kegs unlinked can lead to build-trouble and cause formulae that depend on
those kegs to fail to run properly once built. Run brew link on these:
rubberband
lame
pkg-config
libtiff
libtool
gmp
libidn2
xvid
nghttp2
little-cms2
libpng
frei0r
nettle
pixman
gdbm
opus
freetype
rtmpdump
libsamplerate
libvorbis
libunistring
openjpeg
jemalloc
bdw-gc
speex
libogg
zeromq
harfbuzz
glib
aom
graphite2
srt
tesseract
cairo
webp
c-ares
gobject-introspection
fribidi
xz
fontconfig
giflib
libvpx
snappy
flac
gettext
libsodium
dav1d
opencore-amr
rav1e
libtasn1
libevent
leptonica
pcre
x264
libvidstab
x265
libsoxr
unbound
jpeg
theora
sdl2
guile
libsndfile
libev
lzo
python@3.9
gnutls

Warning: Your Command Line Tools (CLT) does not support macOS 11.
It is either outdated or was modified.
Please update your Command Line Tools (CLT) or delete it if no updates are available.
Update them from Software Update in System Preferences or run:
softwareupdate --all --install --force

If that doesn't show you any updates, run:
sudo rm -rf /Library/Developer/CommandLineTools
sudo xcode-select --install

Alternatively, manually download them from:
https://developer.apple.com/download/more/.
You should download the Command Line Tools for Xcode 12.5.Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

何をどうすれば良いのでしょうか、翻訳などしてもわからないので助けていただきたいです。