THe display daughterboard has more pins than the Atmel Due board has on its digital header. The assembly instructions don't show a closeup of this or provide any information about how it should be aligned.
Which pins on the display correspond to the Due's GPIO header? From the traces on the board it looks like I should have the four extra pins hanging off at the top (i.e. display pins 1/2/21/22 not connected) but that's just a guess.