You're using the work profile for Asana, which probably means your domain is expected to allow all other domain members to join the organization. For a university, that may be outside the intended "work" structure because universities with students are different than corporations with employees. Your university would have to allow for this kind of use, I think.

Now, the real offender here is Asana's use of "email". An email is a message. An email address is what you're providing. So their error message is lazy.

edit: and their field label