The pitot tube test and ground sensor test must be performed at 1m AGL(above ground level).
Indeed if the UAV is let on the foam stand, the ground sensor will not be able to perform the test, and an error message will be displayed on your tablet, preventing take-off.
Remember : From Step "6 Final Checks" of the pre-flight checklist, grab the UAV in one hand, place it at least one meter above ground and perform the pitot test with the other hand. The ground sensor test will be self performed by the UAV few seconds later.