My ebooks download with extension .acsm. I connect my Kobo eReader. I open the .acsm file with Adobe Digital Editions. I get "Error: Check Activation". Adobe Technical support cannot help and refer me to this forum.
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..
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.
I have th e same problem and have done everything you stated to no avail so now what?
Me too. The Adobe tech support just said that the software was no longer supported and pointed me here.