prerequisties were all satisfied. Pedal brake is applied, vehicle in Park. That's pretty much it. I used Ford IDS, VCM II to recalibrate this transmission today.
Just to make sure I tried it second time, again it failed at exactly the same step which is Apply WOT to learn clutch travel points. It immediately says adaptation failed. Worse part of it is in the step before this one, maxisys goes over the TCM and erases all the adaptive memory such as shift points, clutch travel points, neutral points etc. After failure, transmission stays stuck in some gear and it becomes totally immobile, putting the gear in neutral doesn't do anything. Only way to move the vehicle around at this point is by lifting the front tires up, or removing the gear shift motors off the transmission and manually putting it in neutral with a screwdriver.