The most common cause of issues with Dynamics 365 for Outlook is not using the latest version and updates. Dynamics 365 for Outlook has a base installation and the latest version can be found here:
https://www.microsoft.com/download/details.aspx?id=56972
After the correct base version is installed, you can install the latest update from here:
https://www.microsoft.com/en-us/download/details.aspx?id=100431
