Music stops playing when phone is locked and power saver is turned on
How can I get continuous playback of my queue without turning off Power Saver (Android)
Remote Desktop
You may want to check the settings for low power mode, if available, on your Android device to see if background playback/activity is disabled. You may also want to check Apple Music app settings within your phone’s settings to see if that functionality is disabled there.
Different manufacturers for Android devices handle low power mode differently with regards to apps, so I can only provide general troubleshooting steps.