Ahh, yeah, PieFed knows about your midwest.social account and won't let you use the same user name here. That wasn't my intention so I'll have a think about what can be done about that!
When you're not logged in, the home feed has posts from a bunch of general-interest communities on it. But once you log in you need to join some communities to populate the home feed. Head on over to https://piefed.social/communities and mash a few of those 'Join' buttons.