Instead of running the entire school on venture capital, which wouldn't make sense (VCs need a huge return per dollar), we use an advance from investors based on the future value of an ISA to offset the cost.
If we work with investors to say that an ISA will be worth $x, we can borrow $x minus interest the same way you would be able to for any other asset.
Of course, that amount needs to be repaid. So it's still completely risk-aligned.