Well the build looks great! lets get you running.
If you download my firmware at the bottom of the marlin page, you don’t need to edit it just flash and go.
I think your problem is the jumpers under your stepper drivers, did you forget them? Sounds like you are in full step mode not 32nd, so you are trying to driver them 32 times there max. each driver should have all 3 jumpers, under it.
You do have the drv8825’s correct?