Hello MikeBooth21,
Welcome to Apple Support Communities! We understand your concern with receiving the spinning colored wheel on your MacBook. We're happy to assist you with this.
Let's boot into safe mode to see if the same thing occurs. Safe mode can help bypass third party software that could cause this issue. After testing in safe mode, restart the MacBook as you normally would: How to use safe mode on your Mac - Apple Support
Also, test to see if this issue occurs with other apps other than Outlook 365.
Next, run first aide on your Mac HD disk to ensure there are no issues:
Repair a storage device in Disk Utility on Mac
Best Regards.