To authorize Email This Issue access the Microsoft 365 account you’d like to fetch emails from or to use to send emails, you must click the Authorization button in the SMTP Connections or Incoming Mail Accounts.

Once then, you’ll be guided through a couple of steps.

Step 1 - Select the Microsoft 365 Account

Step 2 - Verify that the authorization was successful

In case something went wrong, an error message would appear here explaining the causes like this: