I worked through large chunks of the book a long time ago (perhaps an earlier version). I agree with the other responder-- if you've had zero stats it may be more difficult, but the author does an excellent job of discretizing almost everything, which means that integrals and derivatives are replaced with adding and subtracting. For this book I think the most advanced math you need is multiplication and division. It's a clever trick that relies on the fact that computers are really good at multiplying 10,000 things by 10,000 other things and adding them up (which is what discretization implies here).
Before computers that was much harder to do so you needed clever math tricks to "do it all at once," which gets you to all the analytical methods -- calculus, etc. Still all very useful! Just hard to teach to a broad audience. Downey really leans into the technical advantage to computers provide and thus can cover a lot of material before getting into complicated math.