Using older versions of Outlook for Mac for personal email and calendar
Hi Sontino Mann,
First, I need to double confirm are you using Microsoft 365 Business exchange online email account ? and do you have Microsoft 365 global admin privilege?
For your scenario, if you are using Microsoft 365 Business exchange online email account and if you are not Microsoft 365 global admin, you may need to contact them in your organization. They can manage authentication related settings from their side for user account.
Here are detailed official documents:
Manage authentication methods - Azure Active Directory - Microsoft Entra | Microsoft Learn
Note: above information is applicable for Microsoft 365 Business standard / Enterprise / Education subscription email account.
If you are using any different subscription email account, you need to provide brief information about it to understand particular situation.
Thank you for your kind cooperation.
Sincerely,
Darpan