I want to share my Apple TV subscription with my daughter. She received the invite, but it doesn't seem to work...

• You should invite her by her Apple ID account, not just any email address.
• Both accounts need to be for the same country (as defined by the account’s billing address).
• Once she has accepted the invite, she will be part of the group, and then she can access Apple TV+ content without having the subscription on her account. Access will be granted on being part of a Family Sharing group with one subscriber. The subscription will not be listed in her library or anything.
• She can also accept directly on the device of the organizer, using the “Invite in person” option.
• The Purchase Sharing option of Family Sharing is not needed per se, for sharing the Apple TV+ subscription. Subscriptions are not considered purchases for this definition.

Family Sharing - Apple

What is Family Sharing? - Apple Support

Set up Family Sharing - Apple Support