Apple Music
why can't I join my family subscription for apple music
iPhone 8, iOS 15
Question marked as
Did he send you an invitation join the family group and did you accept it? Also see the 'If you can't accept the invitation' section in:
Set up Family Sharing - Apple Support
Does the Family Organizer have a Family subscription to Apple Music?
Get an Apple Music family subscription - Apple Support
If so, you might be able to fix your issue by turning Sync Library off for all of your devices, then turning it back on again. Learn how.