If this happens go to your computer and plug in your headset say allow from this computer than allow unknown sources, if you do not have a computer than you may do this in the headset when downloading bmbf or any other game it can pop up, after that try deleting beat saber through bmbf by going to tools and click delete BS, BS means beat saber. Then wait for it to be deleted and don't worry all your songs and mods will be saved.

Now reinstall beat saber from the Oculus store because I am using the Oculos quest 2 then once that is done restart bmbf process and then sync to beat saber and then it should work if it doesn't then let me know.