https://lemm.ee/post/lemmyverse.net 404'ed for me. I think you just meant https://lemmyverse.net.
The issue isn't really about finding communities, that's pretty straightforward - you either click "All" and see all of them, or you go to another instance to see just theirs.
However, to subscribe to an instance you need to be logged into your own instance. What's missing is the ability to filter the "All" list by instance. That way you can browse and discover comms from other instances, without going through the massive list of every single one.
As it stands, you have to find the instance from one page, then go back to your own instance, click communities then all and then search for each comm you want to subscribe to, one by one.