What do I do with the !community@instance links? - eviltoast

The links like !NoStupidQuestions@lemmy.world.

I have had a pretty bad time making those work. I have tried searching for them at the communities page, and removing the exclamation mark and pasting them on my instance (lemmy.world/c/NoStupidQuestions@lemmy.world).

Some times one of those works, other times my instance finds nothing. And if I go directly to the home instance of the community, it doesn’t bring my login.

What is the recommended way to use those?