I can’t add students. The page says "username already exists"

Usernames must be unique across all Typing.com (not only your school). If you see an error telling you that the username is being used by another user, you must edit the username. e.g. if the username fernandocote is already being used, you should change it to:            

-cotefernando

-fcote

-fernandoc

-fercot-2019