It’s currently “invite only” for instructors (mostly just to prevent abuse of the computational resources for, eg, crypto mining). If you shoot me a quick email (travis@pathbird.com) I’d be happy to set you up with a course.
You can demo the student experience with code JULIACON2020 as well.
I write a lot of Jupyter notebooks at my main job and I also lecture at a university thus Pathbird seems relevant.