Error: E_ACT_NOT_READY

Windows:

    Close all applications.
    Press WINDOWS + R.
    In the Open text box, type regedit and then press Enter. The Registry Editor opens.
    In the left pane of the Registry Editor, locate the following registry key: HKEY_CURRENT_USER\Software\Adobe\Adept
    Remove the Adept Folder.
    In the Confirm Key Delete dialog, click OK.
    Close the Registry Editor.
    Open Adobe Digital Editions and reauthorize..

Macintosh:

    quit Adobe Digital Editions.
    Navigate to /Users/Library/Application Support/Adobe/Digital Editions and drag the activation.dat file to the trash.
    If you are using 10.7, see https://helpx.adobe.com/x-productkb/global/access-hidden-user-library-files.html
    Open Adobe Digital Editions and reauthorize.