https://www.reddit.com/r/PleX/comments/qxwocm/i_set_up_plex_for_audiobooks_and_i_pretty/

Super high level:

  1. Use AudiobookMaker AudiobookBuilder for Mac to merge all the audiobook files into 1 big m4b file. Make sure the book has the proper book name and the author.
  2. Create a new music library and make sure ‘Store Track Progress’ is checked, and prefer local metadata is unchecked.
  3. Install the Audnexus agent (https://github.com/djdembeck/Audnexus.bundle) and use that for metadata for the audiobook library
  4. On your iPhone, install Prologue and hook it up to your Plex server.

Prologue will give you all the features you expect from an audiobook player, remember playback position, speed up and slow down with pitch correction, and bookmarking.

If you’re not in the Apple ecosystem, I’m sure tools exist for steps 1 and 4.

The nice thing with using Audnexus, is that it adds proper sort tags so that series show up in the proper order.

EDIT 1: This was inspired by this Github post: https://github.com/seanap/Plex-Audiobook-Guide

EDIT 2: The App I use it called Audiobook Builder, not Audiobook Maker.

What I did: used Libation to download from audible Install the Audnexus agent and use that for metadata for the audiobook library