I activated 2013 theme, and couldn't even signup under another name. With the form completely filled I was also unable to login in the "Already have and account? area in the course signup page. Again, it just tells me I have to fill out all the entire form.
I also activated the Coursepress theme to try the "sign up!" in the Courses area, and got the same error messages. At least we can see the form and fill it out, but it's still pretty useless. It seems it is only from the actual CoursePress module in the course that I'm unable to signup, but who would know you can't just signup when you enroll?
On the plus side, I was able to log back in on wp-admin area with my admin password to send this form.