It used to but that way but it confused people since not many know what bitcoin is, use a disposable email for your privacy
Site tells people to topup by small amount the first time like $1 so they figure out how it works.
You can download from the free site without registration
https://openlibrary.io
Tho the "cheap" collection is 5x larger and has Wishlist
I'm trying openlibrary.io , If I type "Xamarin" I get
nothing found for this query which logically means there is nothing found ... , If I type "C++" I get some results but If I type "C#" nothing happens (I only see the same white page with the TextBox and button to search), I assume It doesn't accept weird characters ?
c#, c++ are funny searches for search due to the characters in there, you can search by isbn etc once login by to ebooklogin.com
as for xamarin the free collection is science oriented not computers, and well its only 600,000 entries at moment (will be 2,500,000 in coming months)
same result on the cheap collection (out of 3,200,000 entries) you get this
https://i.imgur.com/RuGzcUE.jpgsend a support ticket and mention your bitcointalk username i will give you free credit to play with
if the book you want is not in the collection you can request it on Wishlist page, example wishlist query: xamarin
https://i.imgur.com/Io36Qza.jpg