The level was divided into 3 sections. I was going through the ceiling on the first part with high speed to come out of the bottom of the middle section and try to reach the ceiling, but my speed was never enough. I just read this now : "If you like it at first, please install the executable; for some reason the webpage version of unity has some troubles with the physics of the game. I'm 70% sure the more challenging levels will be almost impossible."
I didn't read that and played the web version, so that might be why it was too hard