Daniel,
The schedule I see for the strength elements are Backsquat, Deadlift, Push Press, Bench Press.
So it depends how you define what is upper/lower/full body.
As these are all compound movements, a case could be made they are all full body. But usually, in a lot of powerlifting templates, the backsquat and deadlift are lower body, bench press is upper body and push press is full body (if done correctly).
So you’d train what your weakness is in the lower body. So if you can’t hit 2BW for a deadlift, then that’s your weakness, SF doesn’t have a standard for back squat, but if you can hit 1.5BW for a front squat, then you should work on your squatting.
Hope it helps.