Communities/magazines are similar to subreddits, but unlike subreddits they can be hosted on servers run by unrelated organizations and still interact. Different instances can and do have different ideas about how things should be run but you can still send messages back and forth unless the admins have blocked it.

The first message is warning you that you’re looking at a community that is not local to your instance. You might not be able to see all the posts from that community on your instance. For example, there may be older posts that never got copied over from long before your instance first found out that that community exists.

If I understand mbin’s code correctly, the second message means that no one is subscribed to the community locally, so your instance isn’t getting updated by the remote source any more. You need to have at least one local subscriber to get updates. If you’re interested in the community, subscribe to it.

I think this is the code that produces those messages if anyone wants to dig into it further: github.com/MbinOrg/…/_federated_info.html.twig

The definitions for the message strings (in English) are here: github.com/MbinOrg/mbin/blob/…/messages.en.yaml