When I was trying to subscribe to a news community from another instance of lemmy, the button read "Subscribe Pending" What does this mean? Does it mean that they have to approve me before I subscribe, or does it mean that the two instances have to communicate with each other, or something else?
Subscriptions to other instances is handled on their end which means there's a bit of delay. It's nowhere near as long as the GUI makes it seem. Really you can click off right away and it will be fine; you don't have to wait.
These can however get stuck sometimes. It's harmless but you can fix it by re-subscribing and then reloading the page.
I thought the same but I clicked off and when I clicked back it was subscribed, it's purely visual.