Make sure to:
-Use disruption weapons all the time against humans.
-Side with Crow at the factory sublevel.
-When you infiltrate the Ghost Gang garage, don't fight but go west down the cave like path and disarm the traps so you will be reaching the intercom. Interact with the intercom and after a Kiss Ass 5 skill check, you will be negotiating with Blue. Agree to reprogram DI, agree to free the synths, take the quest item from his desk in the room behind him and leave for the steeltown gates.
-Side with Crow at the gates battle*
-After reaching the spire, free the synths and when you go back to the admin level, Blue will be there and achievement will unlock.
*I also did another playthrough where I sided with Crow at the factory sublevel, sided with Markham and incapacitated Crow at the gates, was nice with humans generally, used disruption weapons all the time and freed the synths but made them to keep working for Markham. This is considered the fourth and best Steeltown ending. Unfortunately, Blue didn't appear in the admin level. That's why I advise you to side with Crow and make her the leader of Steeltown.