In other cases where an institution needs to be verified, it may take up to a month to confirm eligibility Ensure the user account being prompted is actually the same ending domain name as the address using to verify credentials and downloading O365 I know you said you repaired but I have resolved this by running repair tool on outlook i would run online repair from control panel I did have a user with similar issue impossible to resolve i finally fixed it by inserting the registry key for sharedactivation of office once it is installed
Checking the remember me box does not work For more information about this change,

Outlook/Office 365 sign in box keeps appearing and forcing sign

Method 3: Reset the user's password.

7
Office 365 Login
If you are the only administrator in your organization and your account is locked, contact
Office 365 Login
I believe he bought Hosted Exchange via Godaddy
Outlook/Office 365 sign in box keeps appearing and forcing sign
It will even pop up while he has been working in Outlook
When trying to use the Skype option in office 365 we get the following message "We couldn't sign you in Change the sign-in status of the user from Allowed to Blocked, and then change it back to Allowed
But we need the SharePoint URL in the trusted sites for other features to work properly, Catch 22 Access all the training and support you need to create a safe, secure, and collaborative learning environment

Free Microsoft Office 365 for Schools & Students

For users Method 1: Wait 15 minutes.

Account has been blocked error when sign in to Office 365
Take a look at this: GPO may not work directly if you have a retail version of office, so in that case you'll need to apply this via GPO registry items rather than using the Office ADMX files
Outlook/Office 365 sign in box keeps appearing and forcing sign
As an Microsoft 365 admin, perform a password reset for the user
[SOLVED] couldn't sign you
Contact your support person to unlock it, then try again