Mp3 download works in a very simple way, perhaps too simple. The app doesn't include any options, none at all. You can't even change the download folder where all your songs are saved. It doesn't let you stream the songs directly from the app either, it just takes you to the browser.
Mp3 download is a mediocre music downloading app that doesn't outperform other apps in terms of content, options or interface. In fact, it often even fails to even download songs.