Why can I see family sharing on the App Store under the description of an app (1Blocker) and yet I can't share it with a family member?

Why can I see family sharing in the App Store under the description of an app (1Blocker) and yet I can't share it with a family member?

Note sure which of the following may have some importance:

1. we have same devices where the pic of family sharing is visible,
2. it is life-long subscription,
3. I want to share the app as a member member of the family group with its organizer