Blimp
On the third screen at the lower left, the condition you need is to delete the part of the stringer that would be below the floor finish level - the screen shows the 150 below - you can lower the overall dimension of the stair to place the stringer in the correct vertical location, but if you don't set the bottom to eliminate the triangle that part of the stringer could show in some views. The stringer default is for connection to a floor edge that has a vertical face that the stringer would connect too.
