We starting to use/distribute Jamf Teacher. We don't have any problems with device at all. But when it comes to Macs the app gets installed but you can't use it. When starting it prompts for server adress, username and password as shown bellow.
I think there's something we missed? For devices you need to configure with an app code. But shouldn't it be the same for computers?
Certainly sounds sounds like you may have missed the app configuration portion of the setup.
Check out the documentation here.
EDIT: That's for iOS. Coming up blank thus far with macOS. I'd suggest reaching out to support or Jamf Success. At least on the Jamf School side of things you can goto instancename.jamfcloud.com/teacher, but my Pro instance gives me a 404 error.....