At first you’re given a large platform. Carry it up until the top, but do NOT ride it up. Carry it down again instead, and you’ll be presented a small platform. Walk near it but do not grab it (or do, but it’ll make what comes later a bit harder). Carry the platform up again, and ride it up. The exit will be to the side but requires the large platform.
The room is named after a common theme of Super Mario Maker trolling, introduced by a level called “Larl Does Everything Twice Twice” - it’s actually not one room but many rooms that looks the same but aren’t.