First, turn off radial culling. Tht shit is doing you no good. Only adding massive fps lag to hammer. (red circle at the top tool bar)
Next:
Why are you even trying to align the walls of the arena with the instances? The instances aare there so you don't need to align anything. The instances should contain the inner wall as well.
Change your ground to a displacement and you should be able to overlap it into the walls without any problems.
Because it's fucked up and the seat vmf was the wrong distance from the center and when i paste it's far away and paste special doesn't seem to work