Note that once you pounce on a survivor and Victor clings to them, they get the Broken Status, and you can see tiny hands over their heads in the bottom left corner of the screen.
Simply run to them once you control Charlotte again and bring them down.
The achivement seems buggy for me, did it a couple times but my tracker still says 0.
Update 2021-01-17 : Managed it a week later on a full day of gaming. So guess they fixed her achievements!