“I created an account and it asks me to login again”He seemed to expect to be logged in after registration. Yeah, why not? Some sites do this, others do not. I also find it mildly annoying to log in after registration, to repeat myself.
It seems to me that he follows the link to another server and is asked to log in again. Different server, another account is needed.
Technically you need another account if you want to post on another server.
For some reason the user landed on a different server with the same look and feel. When challenged to login (again in their experience) they got confused their credentials wouldn't work. The new user expected a single-sign-on for 'lemmy the social medium'.
Could be an early adopter issue that'll be solved over time with wider use and more content, and people get to know what to expect from federation.