Hi
My name is Daniel. I am an Independent Advisor.
Let's isolate this issue to find out if this is an account issue or an Application issue.
Could you please open a new incognito tab then go to https://teams.microsoft.com by using Google Chrome or Edge as a recommended browser. Please let me know Can you successfully log in?
For troubleshooting purposes please make sure you disable Firewall, Antivirus, VPN/Proxy & Adblocker for a while.
Disclaimer:
Please note, this is a peer-to-peer support forum meaning I'm just fellow regular MS Team forum users like you who are trying to help other MS Team forum users with their MS Team issue. So in this case, I'm Non-Microsoft Staff I don't have access to your account nor I'm authorized to do so. I hope we can have a mutual understanding from the beginning to prevent misunderstanding.
Kind Regards