The project projection is 26918 and the polygons are around 1285596223 in area (not sure of the unit there, I think derived from that projection?). I just noticed that the polygons have slightly different area, I am thinking due to the projection? Perhaps this is making a little more sense now why each map doesn’t have the same scale/size and that I would likely need a more trapezoid shape to get equal area and for the atlas to line up better.