One member of the Family Sharing group, preferably the organizer, should get the Apple Music Family subscription. The Individual or Student subscriptions cannot be shared. You have to join the group with the Apple ID as used on your devices.
Family Sharing - Apple Support
Set up Family Sharing - Apple Support
Get an Apple Music Family subscription - Apple Support
The Family Sharing organizer should activate the option to share Apple Music:
Apple Music users should activate the Apple Music features in Settings or Preferences on their devices. And also turn on iCloud Music Library for more features with Apple Music.
Get help with iCloud Music Library - Apple Support
If you can’t see iCloud Music Library on your iPhone, iPad, or iPod touch
First, restart your iOS device.
If you still can't see it after the restart:
1. Turn off iCloud Music Library and then turn it back on.
2. Sign out of the iTunes Store and then sign back in.