The best way that everyone can show support is to follow/star the github repo, test new features, open a discussion with ideas on how to improve the project. Join the discord server.
As you can see, this documentation could really use some support.
This section will eventually give more info on setting up the project locally and contributing.
See this discussion on setting up the audiobookshelf server & web client.
See mobile app readme for setting up the mobile app locally.
PRs welcome and highly encouraged. Before working on an issue/feature you should post about it so we don't overlap.