Navigate to a web page with a download button or link. It may have several of them, or just the one. The point is to find out if the one you see is real or not. Hover the mouse cursor over a link or button and you will see a small bar appear at the bottom of the window.
How do I know if my download button is real?
Another way to tell if a download link is genuine is by hovering over it. Every major browser will show you a little tooltip with the destination URL of the link. If you see googleads or something similar at the start, it is not a valid download link.
How do I get the download button link?
In Chrome - run download as normal - then go to Menu - Downloads - and you should see the direct link which was used. Or press Ctrl + J to open the window. You can use the LiveHTTPHeaders extension to determine the actual URL of the file being downloaded.