Do the obby until you're at the platform right above the sign.

Go up against the wall, make your camera straight with your character, shift lock, and go left until you're about to fall.

Unshift lock and move your camera to the right until you see the wall that holds the ladder you're supposed to jump to.

Shift, unshift lock, and press comma, or whatever the button is that moves your camera left, three or four times. You can tell if you pressed enough when your camera zooms in.

Shift and move backwards, then after a while move right.

If you did it right, you should be a couple jumps away from completing the obby.

It should look like this: