To download your mp3 files to a PC or Mac computer, simply use the download links listed in the ‘Downloads’ section of your account, or those found in your order confirmation email.
Android devices respond in pretty much the same way desktop computers do, and there shouldn’t be a problem downloading an .mp3 file to an Android phone or tablet.
iPhones or iPads don’t allow .mp3 music file downloads (by default), so it is best to download the files to a computer first. Doing it this way means that you can add the music to your computer’s iTunes library and then add it to your iPhone or iPad’s iTunes library too.
However, if you don’t have access to a computer and you don’t mind installing an app on your iPhone or iPad, there are a number of apps available which make mp3 downloads possible (eg. Aloha).