Audible books purchased from Audible do not appear in iTunes

Windows 7. The audiobook I purchased does not appear in itunes nor in C: Users Public Documents Audible Downloads (or any other location on my computer).
It appeared in my iphone at the time of purchase of the book, when I downloaded the application for the phone.
I have tried several times to do it with audible manager and audible download manager (there are clear instructions on the internet) without success. The basic problem seems to be that it can not be downloaded to my computer. This is where iTunes, audible downloader) is looking for the book.
At Audible in Amazones, where my purchase appears, the "Download" button sends a page to a page containing several phones, tablets, etc. on which I can download the application for audible. BUT the computer icon and MP3 files (including iTunes) is grayed out.