"However you can subscribe from another Fediverse account, for example Lemmy or Mastodon" I've been trying to do this for ten minutes and still can't figure it out - Lemmy.world

Supposedly I can subscribe to stuff from other fediverses, in fact it’s one of the main selling points of the fediverse, but I can’t for the life of me figure out how. "You are not logged in. However you can subscribe from another Fediverse account, for example Lemmy or Mastodon. To do this, paste the following into the search field of your instance: " Except nothing ever shows up in any search, either in community searches or the top search bar. It doesn’t even look like it’s trying to search. I also can’t find a place to just paste what fediverse I want to sub to. Does this just not work or am I missing something obvious?