Audio books for DS to listen to on Google speaker

[drspouse]

DS has a Google Mini for his room and we cast podcasts (quite a few stories on there) and books from Google Play Books to it.
We have bought a few audio books but it seems impossible to rip them to cast to the speaker. We have a success rate of about 1 in 4 CD sets - so we bought Lion the Witch and the Wardrobe, and Harry Potter, and it will rip the first but not the second.

We tried Audible but it won't cast to the Mini either. We have Android phones though I do have an Ipad but I don't think that will help.

The Google Play audio books are SO expensive - so £15 for one Harry Potter book when the audio book is £6 or so.

Any suggestions?? thanks!

this might help, it explains how to use audible on a google mini device x
www.businessinsider.com/how-to-get-audible-on-google-home?r=US&IR=T

We tried casting and for some reason it doesn't work.

We don't sit near enough DS bedroom in the evening (when he listens to books to go to sleep) for Bluetooth to work.