Someone from the instance you are logged into must sub first. Until a singular user from a instance subs, you won’t see it auto populate. If you want to be the one to initiate it, login on the instance you want to see the sub using your web browser and use the search function. You may have to search by !community@instance. Sometimes there is a delay in the search, so give it a few seconds.

deleted by creator

I see it just fine when I clicked your link. I am guessing it has to do with the growth/user load of Lemmy.world. Hopefully the instance mods will be able to sort it out. For shits and giggles, create an account on a smaller instance and then visit it from there. I have a few accounts spread out amongst instances (started exploring the fediverse a few weeks ago to see how things work). I have been having trouble on my lemmy.workd account last few days, so I have played around on the other ones and don’t have as rough of a time accessing and posting. Will eventually go back to the lemmy.world account when things improve. Just a matter of time.

Copy the link and post it into the search bar on the remote instance. It might need to be refreshed a couple times before it shows up.

You have to search for it with its full name on the target instance, for example !metalvinyl@lemmy.world (not sure it’s the correct handle, fix the name yourself if it isn’t). That way the instance in question learns it exists. And after someone subscribes, it starts pulling the content regularly.