After opening Outlook the following pop-up is shown:

EV Client log shows the following error:
This version of the Enterprise Vault add-in is not compatible with the Enterprise Vault server (V9)
A std::exception has been caught: Enterprise Vault add-in disabled due to a problem with the current configuration.
FUI: Not loading UI as action map is empty. Is the user enabled?
The user experiencing this issue is not provisioned in EV yet.
If the user mailbox is not provisioned yet, follow the below steps:
1. Check the latest Provisioning Reports at %Enterprise Vault%\Reports\Exchange Provisioning, and Search for the affected user.
2. If the user is not present, add it in the appropriate Provisioning Group, then run the Provisioning Task.
3. Restart Outlook on the client machine.