good morning i can assist you with this
do you know where you audio books are in your mac book
do you currently have an books on audio and if so...where are they located
on your mac mini?
can you download them to your machine?
1. Go to Audible.com and set up an account if you don't already have one.
2. Choose and download an Audible audio file.
These are files whose names end with .aa.
3. Drag the Audible file to the iTunes window.
please let me know if this was helpful remember my purpose here is to help you till you reach a satisfactory solution
after you download it please follow the instructions i provided and let me know if it is working ...i will be on standby until then ....good luck