"Spool mode" just refers to that mid boost area where we don't necessarily want closed loop correction turned on, because we are usually moving through that area pretty fast. It enters that mode above 100-105kpa. This is where closed loop correction will turn off. A timer also starts at that time which is used for the "spool mode time limit". Closed loop correction will come back on if that timer expires (no matter what the MAP reading is), or if the MAP reading reaches the "Spool mode max MAP" setting. The time limit setting is sort of a back up in case you never reach the MAP setting, but still want correction to come on at some point.
If someone was using a 2-step to launch, and you were building boost to say 15psi at the line (approx 200kpa), then set the spool mode max MAP to something higher than 200kpa, like 220 or something. Also make sure the timer is set high enough to not override the MAP setting. This will disable closed loop correction while in that boost range.