I have a similar issue. When I first open the quickadd package it gives
me gatekeeper warning, but then I click cancel and it opens the
installer. Then I can quite and open the installer with no issues. Check
and signatures are there.
Just started testing today and ran into the 3005 error on all our MBAs.
I do think you guys are right and the issue is full screen Safari. We
are doing more testing now and not seeing the issue once clear
directions are given to not go into fullscree...