microsoft account doesn’t exist

I bought the university edition of office last month and I downloaded it onto my desktop. I know would like to download it on my laptop being that I am going to be traveling and will need my laptop to do school work. As I was trying to download it onto my laptop today, I went to sign into to my office account, it is say it doesn't exist. So, I even tried going to go and create a new account, where there it told me that my email address was already in use. I still cannot access it, what do I need to do?