Using Classic Outlook on Windows for personal email, calendar, and contact management
Hello Kenson Lau,
Thank you for posting to Microsoft Community. We are happy to assist you.
To help us narrow down the issue that you are facing, kindly share a screenshot of the error page.
Meanwhile, if you do not have admin access kindly reach out to your admin to check if IMAP is enabled in Microsoft 365 admin center. Sign in to Microsoft admin center > Users > Active users > select the user > mail > manage mail apps.
We look forward to hearing from you; Please understand that our initial reply may not always immediately resolve the issue. However, with your help and more detailed information, we can work together to find a solution. Thank you for your cooperation.
Sincerely,
Simbarashe | Microsoft Community Moderator