Update: This should now be resolved. 6 pm PDT.
Adobe had an unprecedented license server outage for most of the day on May 15th (PDT). Users have experienced issues checking books out of our lending library, mainly getting various Adobe errors. We are still trying to resolve the issues resulting from Adobe’s server outage and hope to fix the problem as quickly as possible. We’ve been in contact with our license provider and we hope to have it fixed soon. In the meantime lending/reading books via the BookReader is still functioning normally.
Apologies for the inconvenience. We’ll update the help page when it’s fixed.