TestFlight 2.1.1 requires a apple id to put in redeemtion code

Our developer is using testflight to roll out an application to us. We use Air Watch and push out app's to the ipads, so our users do not have individual apple id's nor do we want them to. We use the VPP program to purchase and push out the application. When the app is pushed out to the ipads, they are prompted to put in an apple id so we are unable to redeem the code until you login with an apple id. How can we push out the testflight app with the redeemtion code in it so users do not need to use an apple id.