For all the achievements in Call of Duty: Black Ops 4 Zombies, besides the ones relating to the quests, you can use casual mode, but cannot
use mutations. My setup for this achievement was:
-Classified; Casual; classic.
-Full bot squad
-ICR and Ray Gun
The easiest way to get this achievement is to hit the box a couple of times, and get guns you feel comfortable with, and also one you need to level up for
Then buy your way to the large elevator on the lower levels of War Room. Go down the elevator and sit in it looking towards labs. If you stay here long enough this should net you
This is based on how well the bots behave, Ive had better luck with them staying in the elevator if it's on the Labs level.
Alternatively, if the box is in one of the two locations on the Office levels, you can get a decent enough set up with your bots to net you