I just experienced the same issue, but even with the "Learn Ruby on Rails" courses I was battling the same issue throughout the course. It's hard to know if you're coding correctly when you cannot view how your code renders on the browser. The whole time I thought I messed something up, but I kept passing the lessons.
I was hoping the RoR "Ruby on Rails: Authentication" would be different, but right off the cuff on the third step of lesson 1 "Not Found" again. I filed a bug hopefully it gets patched so I can keep learning Rails.