Accessing Microsoft Teams Free using personal or organizational credentials
Hello,
I am afraid you were given the wrong information. If you can sign in to your personal Microsoft account without any issues, then the instructions for unlocking a Microsoft account do not apply to your situation.
This is also not something Microsoft Support can resolve directly. Since the lock applies specifically to your guest account within an organization's tenant, only that organization's administrators can review and unlock it. Please let the organization know that their internal IT department needs to investigate and restore access.
Microsoft does not have the authority to manage or unlock guest accounts or user accounts that belong to an organization's tenant. Those accounts are entirely managed by that organization's administrators. If they need assistance, they can contact Microsoft Support through the Microsoft 365 Admin Center.
Think of it like visiting a company's office. If your visitor badge stops working, you would not contact the company that manufactures the badge. Instead, you would contact the business that invited you. They can verify your access, issue a new badge if necessary, and contact the badge provider if there is a technical problem.