For Mac or Macbook: best quality - lossless, large file. Choose Flac at download
You can play Flac files in Quicktime as individual files, however, for a more enjoyable listening experience, best to install this wonderful free Vox music player, click on icon to install it:
Once the audiobook download is complete, open the file and click unzip. All the tracks will be visible, select them all Right click and open with Vox.