I have successfully opened EPUB library loans subject to DRM prior to summer 2015, but since have encountered problems on each download and transfer. I have tried all of the troubleshooting advice received from Kobo for the Glo with no success this time, including Factory re-sets, re-authorizing, re-transferring, etc. Kobo suggests that this may be an ADOBE issue.
Which error message you get exactly?
Can you open the eBook under Digital Edition?