The Beach Volleyball app uses Firebase which includes Google Analytics. Basic anonymous information like frequency of app use are recorded for these purposes. This anonymous data is used to help improve the app.
Your IDFA (on iOS) and Advertising ID (on Android) are not collected. For more information, go here and here.
A phone number is not required. It simply allows others to invite you using your phone number if they know that instead of your account name/username.
If you grant location permission, the app will access your location while you have the app open, in order to show nearby courts and events. When the app is closed, the app can no longer access your location.
None of this info is shared with 3rd parties, however it may be stored on Google Cloud.
Your email is not shared or used for any purpose other than allowing you to log-in and occasional marketing emails (which you can opt-out from).