Onshape Associate Certificate Exam

Every time I try to login, it says my "username / password is incorrect." FYI I'm using a school / student account. I've checked my login credentials multiple times, and I can't find any error. How can I fix this?

I am administering an Onshape Associate Certificate Exam and 3 out of 10 people can't log in to the enterprise files. It keeps telling them that their password is incorrect when they just used the same credentials to sign in the the exam etc. Any advice…I already wrote to support and haven't found a solution anywhere…