Can you take a look at this technote?
Enterprise Vault client will not install on Outlook 2013 x64 (Office365 ProPlus subscription)
http://www.symantec.com/docs/TECH214359
Let me know if that helps.
This is an on-premises Exchange installation with on-premises Enterprise Vault for mailbox archiving.
The only feature of Office 365 used in this instance is the subscription for Office 2013 - we have several clients that are moving in this direction to eliminate the one time cost required to purchase office for all users.
The issue only effects the ability to use the Office Add-In for EV inside Outlook. I am not sure if the problem is the combination of Windows 8.1 and the subscription version of Office 2013 or if it is just the subscription version of Office 2013 that is the problem.
The add-in did not display in trust center in Outlook so Outlook did not even know it existed. Uninstall/Reintall of the add-in had no effect nor did manual registration. The only fix was to not use the subscription based version of Office on Windows 8.1.
Also note that I was using the latest EV plug-in - 10.0.4.
