Perhaps it works similar to downloading files from gutenberg and then transferring them to the iPhone, to wit:
0) Download the file onto your PC1) Email it to yourself2) Open your email on your phone3) Select "tap to download" inside that email message, on the icon of the file4) Once it downloads (clockwise inflation finishes), tap it again. It should then open up a list of places for you to save it. If you have a audiobook-reading app installed, it should be listed as an option. If there are more than one options, select the one you prefer.
Hope this helps. - B. Clay Shannon

      From: Kent Rasmussen <[log in to unmask]>
 To: [log in to unmask] 
 Sent: Thursday, March 1, 2018 3:38 PM
 Subject: Re: Henderson’s Biography
   
Susan, I get the part of downloading an audiobook to one's computer. What=
 I
don't get is HOW one transfers it to an iPhone so it can be listened to
through the audible.com app or in any other way.