When you click on the "get it" button from the game description, you go to a first webpage with a second "get it" button, and when you click on it two things should happen at the same time: your download will start, and you'll be taken to the donation request page.
Donation is optional.
If we can't offer the game for download for some reason (see
"what is abandonware" on the requests board rules), the "get it" button will be replaced by a different button or notice.