Is this what you are looking for? I have attached the file with my solution of using Floor & Wall. Simply pick the faces you want to machine rather than curves. You can set your Stepover to Passes and set the number to 3. However, it seems three passes aren't enough to clean up the entire floor as it is just over 30mm wide.
is there any reason why you want to use the Surface Contour application.
I would suggest to use the Floor Wall operation. I noticed that you wanted to make three passes, but this is not possible with a diameter 10 tool, because the width of the red floor is 30.5429 (see picture below)
I made a video for you, which you can see below. I switched the tool to a diameter 12 tool. You can also add an additional pass in the Passes option in Floor Wall.