MakeICT fires to Cone 5, which is midfire and glazes used on the midfire stoneware need to be able to fire at cones 5-6.
In contrast The pieces Evans sells premade to glaze are low fire and need to be fired at Evans because those pieces need fired to cone 06 which is much cooler than cone 5 or cone 6. That low fire clay will melt at the higher temps and ruin the kiln shelf in the makeict kiln. Also for those Evans pieces glaze rated for low fire is needed (most of the glazes at makeict are rated for midfire only)
Maybe this chart will help.
