Kiwi Farms

So I picked up Tekken 7 awhile back (on the PC with a controller), and I'm not a regular fighting game player. Whenever I try to do characters' combo moves, they seem to only work whenever they want to.

I'm unsure if I'm pushing the control stick too fast, too slow, or something else, and I don't have much for reference. (I have a handful of other non-fighting games such as Metal Gear Rising and Bloodstained which included special moves that required some control stick combo, and I haven't had as much trouble performing them as I have in Tekken 7). If anyone has any advice on this, I'd appreciate it.