Error adding Exchange account to Outlook Application

I am now getting an error message in adding my Exchange account to Outlook Application. The error is couldn't setup your account. Contact Email Admin. We have tried Autodiscovery in registry already HKEY_CURRENT_USER\Software\Microsoft\Office\x.0\Outlook\AutoDiscover , no luck. Also check with these keys HKEY_USERS\DEFAULT\Software\Microsoft\Office\16.0\Common\Identity. We have tried new profile, tried Microsoft 365, Exchange, and Outlook.com but all of them shows same error. I can login with my phone, tablet and https://mail.premium.exchange/owa/auth/logon.aspx website. The issue is just adding in Outlook Application using computer. I am using Microsoft 365 subscription. Please advise for the steps we could still perform. My account is not managed by an Admin , so there's no way we could enable Modern authentication.