Are you experiencing this issue below in your Dynamics 365 Integration with SyncApps?
The error above is caused when you haven't been able to create an "app password" when using the Multifactor Authentication.
If using Multifactor Authentication, you will need to create an "app password". How to create one? See the link below:
Once created, head back to SyncApps and rerun the sync. The issue should now be resolved.