Hello,
what exactly do you mean by 'client is disabled'? do you mean the Enterprise Vault Add-In is disabled? Or do you mean the user is disabled for archiving?
In general, you have provisioning to have users get archiving policies. In your provisioning group, there is a checkbox that states 'archive mailboxes in this provisioning group' (tab General), and one called 'automatically enable mailboxes' (tab Archiving defaults). you need to have both selected.
In addition to this, the mailbox of the user needs to be synchronized for the settings to be known in the mailbox.
You can check a user by opening the EV console, expand targets. rightclick Exchange, select 'show policies assigned to mailboxes' (or whatever it is called). Have all of the Exchange servers inthere selected, then key in the lastname of the user you want to check. click search. that should show the user, the assigned provisioning group, and the policies the user has.
When that is ok, you can (in the consola again) click the 'enable mailbox' icon, select th exchangeserver that has the mailbox, key in the name, and see if that brins up the user. If it does, he is not enabled for archiving. If it does not show the name, the user is enabled (rough check).
As for the add-in not being enabled, that might be related to the way it is installed. You can try to perform the following:
On the affected workstation, first have the user close Outlook. when closed, browse to C:\Program Files (x86)\Enterprise Vault\EVClient\x64 and run resetevclient.exe
If that throws an error, you might want to do it using an administrator account.
when done, open Outlook again, the add-in should now be enabled.
Users might have to close/open outlook to have the client enabled after it has been installed.