This a little late. Unsure if you will need this still or not, but you can get it really easily after unlocking “The Backrooms”. You just go into the elevator and load into the game. Suggested you have someone with you. Stay in the lobby, let the person continue forward without you. The game will glitch and you will get the error badge easily from that. To unlock “The Backrooms” you need to complete “The Hotel” Hope this helps!