Issue solved.
My steps:
1) Backup folders from /Users/<your user>/Library/Group Containers/ to a another folder or external drive;
In order to view the Library folder go to finder, select Menu > Go (and press Option key on the keyboard)
- UBF8T346G9.ms
- UBF8T346G9.Office (this is where your account is at)
- UBF8T346G9.OfficeOsfWebHost
2) Delete the folders mentioned above (ensure to clean the Trash);
3) Open Outlook. The app will build a new Profile, let it do it. As soon as you are able to open Outlook, select from the Menu Outlook > Activate. Enter your Office 365 subscription login info and finish. Quit Outlook when done;
4) Restore the backed folders to the folder described on step 1);
5) Open Outlook. Enjoy. =)
It worked for me. Hope this works for you too.
Regards,
Federico