The video has access restriction, you should enable it.
Anyway, Vecnazak published a series of video guides for all the achievements. They're hard to find because Youtube algoritms don't show them...
Here is the video on how to do it:
go to 2.34 to see how he did it (but there are other combinations of springs as well to make it in 5 too). I just retried on 1.21 by resetting my achievements and I got it no problem.You must use the bottom ramp and never touch the ground, not even slightly.
Also, anyone except Sonic or Ashura is able to climb the wall at the end of the level to go back and retry.