Hi ,
Please check your host file and try to activate again:
Reset the hosts file:
Windows:
Choose Start > Run, type %systemroot% \system32\drivers\etc, and then press Enter.
Right-click the hosts file and select Open. Select Notepad for the application to open the hosts file.
Back up the hosts file: Choose File > Save As, save the file as hosts.backup, and then click OK.
Search the hosts file for entries that reference activate.adobe.com (for example, 127.0.0.1 activate.adobe.com) and delete these entries.
Save and close the file.
Mac OS
Log in as an administrator to edit the hosts file in Mac OS.
In a Finder window, choose Go > Go To Folder.
Type /etc.
Select the hosts file and open it.
Back up the hosts file: Choose File > Save As, save the file as hosts.backup, and then click OK.
Search the hosts file for entries that reference activate.adobe.com (for example, 127.0.0.1 activate.adobe.com) and delete these entries.
Save and close the file.
If still the same issue then try updating Application Manager: https://creative.adobe.com/products/creative-cloud, launch CS6 and enter the key when prompted and let us know whether it worked.
Regards,
Romit Sinha