Why am I directed to different audio series while listening? What is auto-play?

Auto-play smoothly transitions listeners to another series in the following situations: 

1. when they've completed the last free/ unlocked episode of an audio series and lack sufficient coins to unlock the next episode, or
2. when they've finished all episodes of the series they were listening to

This ensures an uninterrupted listening experience and has also proven beneficial in helping listeners discover new series they might enjoy.