If you do not need to download the files for offline use, you can stream them:
Look for playlists that contain all the lessons to ensure you have the full curriculum. How to Maximize Your Listening Practice
Understanding this distinction is the first step in your search. If you have the old "Nueva Edición" with a physical CD, you already have the audio files. If you have the "Plus" edition, you will need to access them online.
Listening to native speakers helps improve your own accent.