Your calculations are wrong. He wants to see the top of the wall at 22x zoom.
The camera spec page says that at full 22x zoom, the vertical fov is 3.4 degrees. Or, 1.7 degrees above/below center axis.
I did calcs to put the center of the FOV at the top of the wall, the lens will show you +1.7 degrees above the wall (so that you can see what is on the wall and not just the very top of it).
Mounting the camera 7.5 meters high means it's 6 meters above the the top of the wall, 200M away. That would mean the camera lens would need to have a 1.7 degree minimum downtilt angle, when it really has 10 degrees. I'm not sure if you arrived at calculations that get to an angle of 1.7 degrees by coincindence, or if you were trying to take the lens FOV into account.
Because we are dealing with such a narrow FOV, I ignored it and just calculated for center of FOV, this gives you a little bit of "slop", since these measurements might not all be perfectly precise.
For a 200M distance you need to mount the camera 35.3 meters + 1.5 meters above ground.