Episode 9: Independence Day
After breaking into the penthouse vault you must use a zipline to escape the area. Before interacting with the zipline you should go to the weapon box and equip the Bold Eagle.

While hanging on the zipline there is a very short scene where you can shoot some enemies on the balcony of the penthouse (3 seconds). Kill one of them to unlock the trophy or achievement.

If you don't score a kill you can exit to the main menu and resume the game. You will now respawn in the penthouse and can try it again.