This is an easy one, to the point where you can pop it right away as your first trophy. From the main menu, select Multiplayer Game, then set up either an online or offline co-op Game (it's unknown whether the servers/connection for the former still work(s), but the latter will always be available if you have two controllers on-hand). Once you've assigned controllers/players to Lara and Totec and begun the game, this trophy will pop during the opening cutscene.