Place the lamp, put the pressure plate on it, place 2 cobwebs over the pressure plate, place a block over the cobwebs. Next to the lamp, place a tower made of blocks, 3 blocks high, and place ladders on these blocks. The building should look like in the attached picture.
Switch to survival mode, climb the tower of blocks and quickly press the spacebar twice and turn on F5 (or fn + F5), when you return from the lying position to the standing position, click the spacebar twice faster, then you will start to avalanche between the tile and the cobweb! just like in the picture.