Every time I try to do it I just end of flying into the ceiling, and I have looked everywhere but I can't find a tutorial on how to do it.

if you are flying into the ceiling, you are going too far in the elevator

ill attach an image of the ub lineup i use for any%

I was just about to make a post asking the same thing LMAO these are so useful omg

Even when I do the setup i just slam into the roof. Is it a special ultraboost or can you just do the normal ultraboost where you shoot the core eject and the malicious railgun.

it is a regular ultraboost, you aim at the place where the 1st image shows, walk straight backwards (just S, no other buttons) once you reach the spot in the 2nd image you stop moving at all and perform an ultraboost

I keep hitting the ledge above the door after the checkpoint, I have spent many hours looking at videos and attempt, what am I doing wrong.

ye idk how to do this lmao. ive only did it like 4 times out of 40 so im not consistent at all