Seems like you're missing the correct permissions on the Azure "app" side, so that the Odoo client can access email on behalf of users.
Check this process, it might help you (config should be mostly the same for 13.0 than for more recent versions).
Thanks Damien, help a lot!
I got the error "Authenticated but not connected" at first. I did the following:
- When odoo opens then windows authentication flow, you have to be logged in as the user that you are trying to set up oauth for (I was logged in as myself)
- We have mfa enabled and I also set that up for the account, not sure if mandatory or the bullet above already solves the issue
A module extension is not limited to using mail and appointment information. You can create applications that run inside Outlook to make it easy for your users to access business information and productivity tools without ever leaving Outlook. Module extensions are only supported by Outlook 2016 or later on Windows.
Click Tools > Options. Click the Mail Setup tab. Select the check box Send immediately when connected, and then click Send/Receive button. Make sure the group All Accounts is selected and select the check box Schedule an automatic send/receive every.