Do the other group member have an Apple ID account set for the same country (or country-like region) as you? Group members should all have accounts for the same country. It doesn’t work internationally.
Do the group members each have a fully configured account, with all the required details, including a verified email address (respond to test message)? Have them edit if needed.
Invited group members should accept or decline the inclusion into the Family Sharing group. If they haven’t accepted yet, then they won’t have access to the shared services.
The other group members wouldn’t have a subscription, only the original subscriber has that. But the others get access to the subscription content by signing in with their Apple ID account as used for the Family Sharing setup. Their settings for Family Sharing (e.g. on iPhone) would show what is shared. They should be able to go to e.g. Ted Lasso, sign in, and watch that.
Do you have normal full access to Apple TV+ on your Apple ID account?
Did you perhaps recently activate Apple One, after having Apple TV+ before? Apple One starts with a 1 month free trial of the bundle subscriptions, for as far as you haven’t tried those before. The non-trial components resume after the trial, i.e. when paying for Apple One. For a seamless transition, such subscribers would need one month overlap.
Did they try the right content? E.g. iTunes Store movies (buy/rent) are not included in Apple TV+.
About Apple TV+ - Apple
Apple Originals - Apple TV+ Press
List of Apple TV+ original programming (episodic/series) - Wikipedia
List of Apple TV+ original films - Wikipedia
Else contact the Apple Support staff for assistance.