After November 1, 2021, only Outlook 2013 Service Pack 1 (with latest fixes) and later will be able to connect to Microsoft 365 services.
Not supported versions;
- Outlook 2007
- Outlook 2010
- Office 2013 versions earlier than 15.0.4971.1000
- Office 2016 versions earlier than 16.0.4600.1000
Outlook 2007 or Outlook 2010 is blocked from connecting to Exchange Online.
Users can immediately start using Outlook on the web through a browser.
If you want to find the outlook version information used in your tenant organization, you can use the “Microsoft 365 Reports in the admin center – Email apps usage. “
Have a nice day !