Enable the Protected Trust Outlook Add-in (If Outlook has disabled it)
If Outlook disables the Protected Trust Add-in, you can easily enable the add-in by taking the following steps:
Open Outlook and click File > Options > Add-ins
Click the drop down next to Manage: and select Disabled Items and click Go.
Select the Protected Trust add-in and click Enable then click Close.
Go back to Manage: and click the drop down, select COM Add-ins and click Go.
Check the box next to the Protected Trust add-in and click OK.
You should now see the add-in in your Outlook's home screen ribbon.