Purchased an audiobook from pottermore shop. How do I get it from my mac to my iPhone?

Purchased an audiobook from pottermore shop. Have been unable to get it from my download file on my mac (os x 10.10.5 yosemite) onto iTunes or ibooks. Have tried to add to library on both iTunes and ibooks, nothing happens. Also tried to move the audiobooks from iTunes to ibooks on my mac and and get the response that iTunes does not have any audiobooks, I have about 10. On my mac they are still in iTunes, on my iPhone 6 they are now under ibooks. This used to be a very easy thing to do. Appears to be easy, just doesn't seem to work. What am I doing wrong?