To enable Grid-on-Screen Logon method, the System Administrator needs to add the necessary authentication method in to the Application's Logon Procedure. Like follows:

Also, the administrator might wish to refine the associated policy named "GridGo":
Navigate to "Administration | Policies". 
At the 'Category' drop-down, select "GridGo", then "SEARCH" button.
Select the context "..." menu on the displayed Policy, then "EDIT":

You might wish to change the length of the passcode, default navigation path, PIN etc.