Can't get Outlook to Open on my Mac

Sorry to hear that you’re having trouble opening Outlook on your Mac. Microsoft indicates that Error Code 44 when refreshing a Microsoft 365 license is usually caused by being signed in with an account that does not have the license you are trying to refresh.

First, please sign in here with the Microsoft account you normally use for Microsoft 365 and confirm which subscription appears:

https://account.microsoft.com/services

If your subscription is listed there, please use Microsoft’s License Removal Tool to remove the existing Office license information from your Mac:

https://support.microsoft.com/microsoft-365-activation-licensing/how-to-remove-office-license-files-on-a-mac

After the tool finishes:

Close all Microsoft 365 applications.

Restart your Mac.

Open Outlook again.

Sign in using the same Microsoft account that shows the active subscription under Services & subscriptions.

One important point: if by “basic 365 plan” you mean Microsoft 365 Basic, that subscription does not provide the desktop Microsoft 365 apps license. However, Outlook for Mac itself can be used for free with personal Outlook.com, Gmail, iCloud, Yahoo, and IMAP accounts.

If Outlook still does not open after these steps, please let me know your macOS version, your Outlook version, and whether Outlook displays another error before closing.

If this answers your query, please click Accept Answer and Upvote if you found it helpful.