To expand on what the previous poster said. Google has to force you to use their app on your phone, in an effort to limit piracy. When you download the music to the device using the download option in the app it gets stored in an encrypted and hidden container. However, if you have a PC you CAN get the music files as MP3's. The site will allow you to download the music to your PC as a clear MP3, you could then copy the music to your phone using a USB cable plugged into the computer. If the site doesn't allow it, the Google Play Music Manager app might.