Teams Account Error

Hello,

I am a student trying to use teams to view online lectures. Unfortunately, I am having trouble being able to log into and open MS teams. I downloaded the teams app, but when I try to open it, it tells me I am not yet signed up for teams even though I have a teams account. When I click sign up, it opens an internet tab prompting me to sign in. Once I sign in, it opens a new internet tab with the exact same message as the teams app, telling me to once again sign up for teams. I am just stuck in a loop and wondering if anyone can help.

Best,

Chris