Hi thanks for using JustAnswer.com I am Cris.
You are trying to transfer iBooks from a iPad to a Kindle? Is that correct?
Unfortunately iBooks cannot be transferred to Kindle. iBooks are pro-priority to Apple as Kindle books are to Amazon. I always recommend purchasing books through Amazon/Kindle because the Kindle app can be downloaded on any device iPhones, iPad, Android, PC or Mac. But Apple iBooks is not cross platform unfortunately.
I know this might not have been the answer you were looking for but unfortunately the correct answer I can provide. you. Let me know if you have any further questions I will be glad to answer them. Please take the time to rate my service and submit at the top.