To download epub books with DRM they should use Adobe DRM which is commonly available. Down load to your computer then use Adobe Digital Editions to load book onto your reader that is connected to your computer. If epub book is DRM free then you can copy and paste book to your reader from your computer. I have downloaded DRM free books directly from online ebook store source to my wifi connected Kobo Touch.
This is a free ebook library manager that most people here use.
http://calibre-ebook.com/