Player 2: Run to the switch on your left by the acid and press it once player 1 is waiting by the locked panels.
Player 2: Head through the nearby portal (behind you) and join player 1 in entering the new area.
Player 2: Repeat the exact same steps as for player 1 (the whole run should have mirrored movements due to the timing required).
Player 2: Once again, follow player 1's steps and run through the portals to the switch.
Players 1 and 2 Together: Hit your switches at the same time and a timer will start ticking away in the background, so both of you immediately run back through your portals and hit the switch on the ground floor together.
This'll drop a metal ball that should be dropped in the round switch near the exit. Voila! Exit open!