Am on apple family for Apple Music but Apple Music won’t work

Hello desire22,

Thank you for reaching out to Apple Support Communities.

Have your sister review these steps to see if the subscription is being shared:

"If you already set up Family Sharing

After you set up Family Sharing, eligible subscriptions are automatically shared with your family members. If your family members can't access a subscription, here's what to do:

1. On your iPhone or iPad, go to Settings, then tap your name.
2. Tap Subscriptions.
3. Scroll down and make sure that Share with Family is turned on. 
4. Tap the subscription that you want to share.

• If the subscription is individual or student, upgrade your subscription to a family plan. 
• If the subscription isn't made by Apple, it might not be eligible to share. To share a subscription, turn on Share with Family under Family Access."

Additional details can be found here: Add a family member to your shared subscriptions

If the issue persists, can you provide a few more details? What exactly happens when you attempt to access Apple Music? Also, which device and iOS version are you currently using?

Cheers!