I’ve read that it should be possible, but my experience seems to show that that is incorrect, that you need a login for every instance where you wish to make a post or comment. Could someone who knows clarify this?
If you need a login for every instance of Lemmy to participate in non-local communities, then that will, I think, be the #1 issue with Lemmy adoption, and the main reason folks bounce off.
If on desktop, you need to interact with content from inside your own instance. For example for you, your own instance is lemmy.ml you visit this website and then subscribe to communities either on your server or another server(important: without leaving the tab of your instance in the browser! Otherwise it will say you need to log in). You find communities either on the All tab or in the communities search at the top of the website.
In the future all this will become easier like it did for Mastodon but for now we have these growing pains.