I have the following on my publish server
I have disabled anonymous access to my adaptive form. When your users try to access this form they will be forced to a login page. On successful authentication you can forward the users to this AF.
So you need to create a login page that can be authenticated against your leap. on successful authentication, I am adding the users to the formsusers group. Only users belonging to forms-users group will be allowed to access the adaptive form

daptive Form. I have set the