Processes in Microsoft 365 Insider for installing preview builds, activating subscriptions, and keeping apps up to date with the latest Insider features.
Apologies, I neglected to check the version linked from the AutoUpdate page.
The latest version (3.15.18011602) can be downloaded from this link: https://go.microsoft.com/fwlink/?linkid=830196 - If you run into issues using that link directly, it can be accessed by going to this page: https://support.office.com/en-us/article/Check-for-Office-for-Mac-updates-automatically-bfd1e497-c24d-4754-92ab-910a4074d7c1?wt.mc_id=O365_Cons_TS_Link&ui=en-US&rs=en-US&ad=U and then navigating to the "Need Help With AutoUpdate?" section of the page.
Let us know if it works after updating to the latest version.
-Jesse