damn near impossible for me 
can someone please tell me how fast or slow it needs to be?
Who are you using?
You have to visually confirm the distance and range. It depends on the character. You might cancel too early, late, or need to delay some things.
im using the girl wit the machine gun.
dont mash. try harder.
You sound new. Aigis is one of the more difficult characters in the game. I’d reccomend Mitsuru or Yu, possibly Chie for a first character. However, if you want to stick with Aigis, try do her trials in challenge mode and watch the demonstrations. They should teach you how to do her basic to intermediate air combos. Use visual cues to help your timing. This will take time, no matter what you do. It’s just a part of the genre.
Just watch the videos of Aigis in challenge mode. It does take practice, so just practice that one part of the combo and see when you need to press up. Sometimes you need to hit two attack buttons then jump (you only get two jumps). Other times it is a matter of going up towards.
just figured it out. I wasnt jumping for each one lol.
Personally I would recommend trying over and again until you nail it. Took me a bit to get down Labrys’ air strikes after playing Chie, timing is totally different imo. If you’re just button pressing it shouldnt be too difficult, pretty much all visual. If you’re trying to throw in strikes and double jumps I personally think the trick is hitting the 2x jump timing after your strike lands so the rest will follow up properly. Initially I was trying to 2x jump too soon after connecting just prior, I needed to slow down a bit. Coming from Marvel, I feel like the inputs need to come out slower.