GAP 4.8.9 installation with standard packages -- copy to your CoCalc project to get it
#g3 f1 6x6 0 -1 0 0 0 0 -1 0 0 0 0 0 0 0 1 0 0 0 -1 -1 0 1 0 0 0 0 0 0 1 0 0 0 0 0 0 1 6x6 -1 -1 0 0 0 0 0 0 0 1 0 0 -1 0 0 0 0 0 0 -1 -1 0 1 1 0 0 0 1 0 -1 0 0 -1 -1 0 1 6x6 1 1 0 0 0 0 -1 -1 0 1 1 0 1 0 0 0 0 0 1 0 -1 0 1 0 -1 -1 0 1 0 0 1 0 0 0 0 -1 6x6 4 1 -2 -2 1 1 1 4 1 -2 -2 1 -2 1 4 1 -2 -2 -2 -2 1 4 1 -2 1 -2 -2 1 4 1 1 1 -2 -2 1 4 2^8 * 3^4 * 5 = 103680 dim6/6-2c