Summer Cam at USA with BUNAC

I have a couple of questions about BUNAC
First of all, I'm Egyptian and live in Egypt, do you guys have any idea if it's possible to attend summer camps?
I was doing my application form on BUNAC and there's a deposit to pay, do I pay it before anything happens, or what exactly is this deposit for? and what happens if I don't get any opportunity with any camp do I get a refund or what happens to the whole sum I'm going to pay (£379.00)

Could someone explain the whole BUNAC idea and how the process works from the beginning I'm looking forward to experiencing the summer camp next summer 2025