There is one more step once you found an community you’d like to subscribe to. Take the link to the community (something like lemmy.fmhy.ml/c/freemediaheckyeah ) and copy it into your home instance’s (the one you’ve made an account on) search page. for me it looks like this:
Sometimes, it will say “No Results.” Just wait a view seconds, and maybe try to refresh. The server it mostly likely retrieving some posts and comments for the first time. Eventually, it will show up, click the result, and you’ll be directed to something like lemmy.sdf.org/c/[email protected] (with your home instance’s domain in place of mine) and you can subscribe from there.