Can't read library books on Kobo Mini because of DRM authorisation problem

[Helen7]

I recently bought a Kobo Mini, with the intention of using it to read e-books borrowed from the library. I use a Mac, with OS version 10.6.8. This does not support Adobe Digital Editions version 3.0. I have therefore installed earlier 2.01 version, which has installed fine. I have downloaded an e-book from the library, which shows up on the ADE library page, and have also bought a couple of books. The books I have purchased are all available to read on my Kobo. But although the books I have borrowed from the library are listed in the Books section on my Kobo Mini device, when I try to open them the message says: ‘Ooops! This document couldn’t be opened. This document is protected by Adobe Digital Rights Management (DRM) and is not currently authorised for use with your Adobe ID.’
 

[Guest]

I have similar problem with Windows 8.1 and cannot authorize downloaded books from library to put on my Kobo