it also says
Single book requests:
Author & Title in the subject line. In the body Paste link(s) referring to the audio edition of book(s) you wish to be uploaded.
Series requests:
Author & Series Name in the subject line. (Please include book numbers needed, ex. 4-7). The body should include individual Titles and Links to each book to assist uploaders searching for your book. Most books are indexed by Title not Series Name..
A link to the author/publishers is fine if it shows each book separately linked in audio for example
https://gardnermysteries.com/books/captain-lacey-regency-mysteries/the-hanover-square-affair/https://gardnermysteries.com/books/captain-lacey-regency-mysteries/a-regimental-murder/ https://gardnermysteries.com/books/captain-lacey-regency-mysteries/the-glass-house/ etc...
Sarah Kozloff site don't, they not merged as a collection but are not listed individually either so who knows whats in audio.
not a big issue, now you know for next time

.
We often get requests for books that are not even recorded, sometimes not even released so insisting on audiobook links shows it exists.