Okay, everything in your lengthy post was exactly NOT what I was seeing. And I finally figured out the reason for it: the site behaves completely differently if

Okay, everything in your lengthy post was exactly NOT what I was seeing. And I finally figured out the reason for it: the site behaves completely differently if it doesn't think the browser accessing it is running on Windows. Then you get the actual installers for download. But if it DOES think you're running windows, the site hands out the wrapper executable. My guess is that the wrapper only works on Windows and they don't want to appear broken for users on other operating systems.