This is the achievement for finishing the final segment of the game after you’ve activated all the lasers. I used this video by PS4Trophies for help as this final segment is pretty challenging at times.https://www.youtube.com/watch?t=1786s&v=0-BuYY4arX8
Be warned that you should not
complete the final steps for this achievement if you’re planning on attempting the Challenge for the achievement. Unlocking the Endgame achievement resets the world and you’ll have to start over in order to attempt the challenge.