Colors listed don't include terracotta which looks like what your site calls redwood. Is this correct? For installation, how many screws are used to hold each arm to shell of hot tub?
I think redwood would be a decent match to a terracotta color.
Not certain about total screw count, but I would imagine a couple up high on each bracket, and probably one down low on each bracket.
We can also have them made with no screw holes so that you can determine the best place to make the holes for your spa cabinet.
If that is desirable, just type ?no mounting screw holes? in the COMMENTS block on the checkout page.