Situation: After installing an add-ins in Outlook 2016, the user has a problem to run Outlook with the add-ins.
Troubleshooting: We find there are two Office 365 running on the computer. One is pre-loaded office 365. Uninstalling the pre-loaded Office fixes the problem.
Also please refer to this article:
How to uninstall pre-loaded Office 365 in Windows 10
The real reason is Pre-loaded Office 365 is 63Bit. Their Add-ins is 32 bit. You must install Office 365 32 bit for the 32 bit Add-ins.
