According to the developer's information and the details on the official website, the software installs as an extension and a Windows application. When you have a download link, the download manager captures it and downloads it automatically. However, I wouldn't recommend using it because it looks dubious.
Instead, use Free Download Manager. It's based on the same principle, but it's safe to use and install.
Download page: http://www.freedownloadmanager.org/
