To share a subscription to Apple TV+ with a small group, like a family, you will have to set up Family Sharing. One of the family group has to take on the role of Organizer, and invite the others by their respective Apple ID accounts. That person needs to have an Apple device (iPhone, iPad, or Mac).
Family Sharing - Apple
What is Family Sharing? - Apple Support
Set up Family Sharing - Apple Support
Some Family Sharing features are optional, but certain subscriptions, like Apple TV+, are shared automatically if one of the group has this subscription.