GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
#g4 f1 6x6 % we missed out --1 -1 0 0 0 0 0 0 -1 0 0 0 0 0 0 -1 0 0 0 0 0 0 -1 0 0 0 0 0 0 -1 0 0 0 0 0 0 -1 6x6 -1 0 1 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 6x6 0 1 0 0 0 -1 0 1 0 0 0 0 1 1 0 0 0 -1 0 1 1 0 0 -1 0 0 0 1 0 -1 0 0 0 0 1 -1 6x6 0 1 0 0 -1 0 0 1 0 -1 0 0 -1 1 0 0 -1 0 0 1 -1 0 -1 0 0 0 0 0 -1 0 0 0 0 0 0 -1 6x6 2 0 -1 0 0 0 0 2 0 -1 0 0 -1 0 2 -1 0 0 0 -1 -1 2 -1 0 0 0 0 -1 2 -1 0 0 0 0 -1 2 2^8 * 3^4 * 5 = 103680 dim6/6-2b