After the key door unlocks, hyper bhop into a wavedash. It is important that the wavedash is started under the lowest ceiling here marked.
After the wavedash, jump and upright dash.

Cornerkick after the screen transition, hold jump, and upright dash around here.
When you reach the peak of your dash height, cutscene skip immediately to have Madeline's Y-Position be on the button.
If you feel you are too low when you pause, you can try to save yourself by buffering downdash and pressing the button before it kills you.