05-24-2015 10:06 AM - edited 05-24-2015 10:08 AM
It looks like Librivox files are .zip files that unzip into folders of .mp3 files.
Are you unzipping them before you try to transfer them? Right-click on the .zip file and Extract to... somewhere on you computer, then transfer the folder.
If for some strange reason you don't have an Unzip program on your computer, 7zip is good and free.