Message: E_ACT_NOT_READY

After installing DE (v4 or v2) on a new MacBook Pro (OSX Yosemite) I am no longer able to download library ebooks on any of my computers with DE installed. The ACSM tokens are either not "processed" by DE, or I see the message E_ACT_NOT_READY. Has something happened to my account? How can I restore service?

The public libraries are unable to help, since it does not seem to be a problem with their Overdrive software.