I have a Sony ereader PRS-300. I have am trying to dowload purchased books from CBD. Each time I try, ADE opens but so does Reader Library. I get the message in Reader Library, that the download failed and I should try again. I have downloaded numerous times using ADE and then transferring to my ereader.
I think you have a 'setup' issue with CBD. They may be the best place to
go for help.