For a Samsung phone: Modern phones already have an unzip app built into, if an older phone, click on the icon to get one without any cost:
Once the download for your file is complete, click unzip and extract the files. Top right corner. Depending on what music player you have installed you will find the mp3 clips ready to play. Most likely in the Samsung music player or in google Music Player.
Depending on your settings it might arrange the files by file size and not necessarily by name or number. Rearrange them so that the numbers go in numerical order and begin playing the audiobook.