What is Voices Plus and how does it work?

https://blog.findawayvoices.com/introducing-voices-plus/

Voices Plus is an optional distribution strategy for your audiobook. You receive extra benefits in exchange for committing to only using Findaway Voices to distribute your audiobook. It's an opt-in, title-by-title program (it's not all-or-nothing if you have multiple audiobooks with Findaway Voices).

If you prefer to upload your audiobook outside of Findaway Voices to one or more retailers, you should choose the standard distribution option instead. 

There's more detail about Voices Plus in Schedule E of the distribution agreement as well as this blog post.