Reading the analog thumb sticks from a ps4 controller for dc motor speed control

ok so im making the hardware proof of concept for an eventual mid scale Bluetooth car controlled by a PS4 controller.
my goal is to have tank controls with the thumb sticks Y axis working as speed controllers. as in the further up you push on the left stick the faster the left motor spins.

here's a link to my GitHub with the code and in the repository are the full example codes i have been using as reference.

im suck in one of those, "i don't know what i don't know" kinda situations, so any guidance would be appreciated