This error occurs when too many computers or devices have been authorized with the same Adobe ID.
Please visit Adobe's support site to reset your ID. Make sure to select Digital Editions for step 1 and Adobe ID and signing in for step 2. Click Still need help? Contact us.
When the option appears, click Chat now to open a chat with an agent. Explain your situation, and he or she should be able to help reset your ID.
Note: You can manage your Adobe ID and device activations with an OverDrive account.