I had an issue where it was not possible to login to Teams web client. It just generated a error that referred to contact your administrator.

AADSTS7000112: Application ‘id’ (Microsoft Teams Web Client) is disabled

To fix this issue we can go to portal.azure.com and sign-in. Select Azure Active Directory -> Enterprise Apps and do a filter as shown below

Select Microsoft Team Web Client and properties. Make sure that you select “Yes” to let your users use Teams in web browser.

Now your users should be able to use Teams in web browser again=)

Hope this can help.