If the books are DRM books you must have already authorized the Galaxy to be able to read the books there; or ???
Most eReaders need to be connected to ADE (Adobe Digital Editions) to be authorized with Adobe ID to permit reading DRM books.
ADE runs only on PC and Mac.
You may have difficulty transferring books to the kobo without a PC or Mac as well;
you might manage it if you can connect so the Galaxxy cas see the files on the kobo.