This guide will help the Keyboard and Hitbox users to finally be able to do 360's and 720's consistently.
and MASHING THEM IS POSSIBLE on keyboard and hitbox too just like a normal arcade stick or pad.
It doesn't get simpler than this

VIDEO TUTORIAL
https://www.youtube.com/watch?v=ic41fBxSj7Q

THEORY
First step: Configure your inputs

on PC version of USF4 you can configure butons for Keyboard 1 and Keyboard 2 in the button configuration section.
However , while playing bother Keyboard 1 and Keyboard 2 buttons function normally. This make it possible to have more than 1 buttons for a single input

Generally I use WASD for movement.
WASD being marked as movement inputs for Keyboard 1 ,
However , I have mapped Spacebar as my UP input on Keyboard 2
This way , i have 2 up buttons , W and spacebar.

If you do not use WASD , you can just mark some other button instead of spacebar that you are comfortable with.

Second Step: Doing the 720

First a normal 360
-> Hold DOWN + BACK
-> while holding it , tap FORWARD
-> without letting go of down + back , tap UP + Punch

Do this whole motion during a Dash or while jumping , or just buffer between any move

Do this motion twice during a dash or buffer it then press the PPP or KKK according to your character to get the Ultra Combo.

Mashing them is possible

Hold DOWN + BACK
and repeatedly keep pressing forward , up , punch or kick