The relevant settings are located in the Exchange Desktop Policy on the Enterprise Vault server.
 

1. Vault Cache tab > Automatically enable vs. Allow users to decide
 

This setting controls whether Vault Cache is forced on users or whether it is elective. In either case, the default behavior is to present the user with the Setup Wizard upon opening Outlook. When Automatically enable is selected, the user can still cancel the wizard, but it will reappear each time the user reopens Outlook, until the user completes it. When Allow users to decide is selected, the Setup Wizard is shown the first time the user opens Outlook, and if the user declines to enable Vault Cache, it presents a short message about how to enable it manually later. It then leaves the user alone in future Outlook sessions until he invokes it from the Tools menu.
 

2. Advanced tab > List settings from: Vault Cache > Show Setup Wizard
 

This policy setting functions as a simple on/off switch for controlling whether the client displays the Setup Wizard to the user upon opening Outlook. In combination with the first setting above, it functions as follows:
 

a. Show Setup Wizard = On, "Automatically enable"
 

Wizard is shown when opening Outlook. If canceled, Wizard continues to be shown each time the user opens Outlook, until it is completed.
  

b. Show Setup Wizard = On, "Allow users to decide"
 

Wizard is shown when opening Outlook. If canceled, Wizard exits and does not prompt again until manually invoked using the Tools menu.
 

c. Show Setup Wizard = Off, "Automatically enable"
 

Wizard is not shown. Vault Cache is enabled for the user without interaction and uses default client settings.
 

d. Show Setup Wizard = Off, "Allow users to decide"
 

Wizard is not shown. Vault Cache must be enabled by the user from the Tools menu.