It may be a good idea to separate the link for PDF and EPUB on DOWNLOAD FROM FREE FILE STORAGE sections.
The needs for this is because the users only need one type of file, usually pdf file. The pdf file is being sought because it can be viewed on chrome and edge instantly without any need to add an extensions, and also to save a bandwidth limitation and time constraints from users perspectives', the pdf file size is much more smaller compare than epub. The time used for downloading unnecessary file can be allocated for another activities.
Let the users chooses what they want to download a pdf or epub file.