SF newbie/ Laura help

First off, I have had SFV for probably about a year now but never really got into it. However I always liked he flashy moves of SF so I am looking to get into it. My big issue is that I have issues pulling off combos when it uses the QCF, QCB, etc. I was using the joystick on my controller, but read that it could be easier using the d-pad (I play on PS4). Either way its still for some reason a bit challenging for me.

Secondly, I am currently learning Laura and I am doing her Challenge trials and I am stuck on her 7th one. For 2 days now I have not been able to pass it. There are times when I should have but the last input shows red. I have to do a Jump HK-Standing HP-QCB LP-QCF QCF K. A lot of the time I get all but the last inputs and when I do get the last input in it just goes red. It is driving me crazy. I don’t want to skip it because then I am learning nothing. My thumb will start to hurt from the amount of tries I do.