That doesn't look quite right to me.
I used a Holywood universal bike rack (3-bike) on my 156SW many, many times without issue - But, the bikes were much higher up than you've got them. In fact, the bottom of the bikes wheels were about level or slightly above the rear lights of the car.
Difficult to tell from your photos, but the rack looks kinda similar to mine. My topmost bar (you have feet instead) was much higher up the rear window and the roof straps went OVER the spoiler without touching it.
The arms (where you place the bikes) were at a much steeper angle, pointing up at about 45 degrees to the rear window.
My rack also has six straps, two top, two to the sides and two to the bottom (underside).
I always placed the bottom of the rack slightly above the rear bumper so that when all 3 bikes were on and everything was tightened up, it just about rested on it.
Hope all that makes sense.