save this post (we’ll be revisiting this a few times)
go to the search function that is indicated by the bulleted list icon
enter the community name (without the @… part)
there’ll be a few results
tap on them, see the posts if you want, and tap the subscribe button and see that it shows joined
go to saved posts, repeat until subscribed to every community you want
Having said that, there’s probably a simpler way to do this. Still early in the learning process.
I did the following on Jerboa