Unable to log into outlook mail account saying I’m logged into outlook 365 when I don’t have an account?

So I have an account with my college that they assigned me to use only for school, its the outlook mail. I tried logging into my account several times and it will take me to a small screen that says I'm logged into the outlook 365 account to click on the this link and it will log me out. On a side note I don't even have a outlook 365 account so how could I be logged into it? Once I click on the link and re-enter my account info it keeps taking me back to that small box. Why is this link not working to log me out of an account I have never accessed before?