Start Play: tap anywhere near the center of the screen.
Resume Play after turning face down: turn face up (this can be disabled via settings).
Volume Up: drag right and hold while playing. You should listen. It will “tick” as it gets louder, and beep when it can’t go further.
Volume Down: drag left and hold while playing. Similarly.
Faster: drag up and hold while playing. Similarly.
Slower: drag down and hold while playing. Similarly.
Back up/jump forward to last place user stopped: Two finger swipe left or right while playing. There are several places remembered. Enable in playback settings.
On the playback screen you can also rewind or fast-forward using the blue buttons. If you hold it for a while it will go faster. The Gear Icon lets you enter settings for more options. Refer to the full website for details. (Under “Getting Started”.)
There is a mini audiobook tutorial you can use as well; it can be loaded from the website.
The website is https://donnkey.github.io/aesopPlayer.