There is a problem with the security certificate on the login page used to access Office 365 including Outlook on the Web, SharePoint, and OneDrive. The certificate expired and engineers are working to update the certificate which will correct the login page errors.
Outlook on the Web, SharePoint and OneDrive – Unable to log in
by Guanti, Reid J. | Jan 2, 2021 @ 9:49 AM | Email, OneDrive, SharePoint