More recent levels of the Android SDK limit access to external storage. This is probably your problem if you are reusing an old project. It has nothing to do with Music Player. Essentially, you cannot access external storage in current Android versions without getting the User's permission first.
The easiest fix is to use the manifest editor to limit the target sdk level to, say, level 28. I use this with my MusicPlayer app and it works fine on Android 10, although of course it would not be accepted by PlayStore. If you want to produce an app for PlayStore then you will need to learn how to access external storage at current sdk levels, which is where ContentChooser comes in.