Why won’t Apple Music open when it is family shared with me?

Hi Despol,

We'd recommend resolving the issue by making sure the subscription has been shared with your correctly. You can get with the organizer and check this information by completing the steps listed here: Add a family member to your subscriptions from Apple - Apple Support that are also below.

"How to add a family member to your subscription from Apple

1. Open the Settings app.
2. Tap your name, then tap Family Sharing.
3. Tap Set Up Your Family, then follow the onscreen instructions and invite your family members. Already set up Family Sharing?
4. Eligible subscriptions are automatically shared with your family members."

Best regards.