The version of Add2Outlook installed is dependent on the version of Outlook.  To upgrade (or downgrade Outlook) you will have to uninstall the version you have first, then upgrade Outlook and then reinstall the Full Add2Outlook install.  The installation program is smart enough to install the correct version. 

Wherever Add2Outlook is installed, log in as the service account

Open the Add2Outlook Console  

Export relationship setups – save to the zlibrary – name it “before upgrade [initials] “
Close Outlook
Uninstall Add2Outlook and the Toolkit
Upgrade Microsoft Office
Reboot
Do all MS Critical updates
Reboot
Install Full Add2Outlook Installation - Right click and install as administrator  if applicable
Install Add2Outlook Toolkit as administrator

Open Outlook and accept the installation, and then start sync and it should operate normally