I think I am missing something. We have an IIS server set up with Web Adaptor managing two ArcGIS Servers. I want to assign users and roles from AD but according to http://resources.arcgis.com/en/help/main/10.1/index.html#//015400000517000000 I would need to have Web Adaptor installed on the ArcGIS Servers as well? Or vice-versa? I understands that it performs the authentication but how to do it from Server Manager? Once I put in my credentials, set the web tier, I would hope to see the AD users and roles so I can assign them.