use offline activation.
disconnect the installed computer from the internet
Launch the product.
At the Serial Number Validation screen, click Having Trouble Connecting To The Internet.
Click Offline Activation and click Generate a Response Code.
Write down the Request Code.
Switch to an online computer and navigate to www.adobe.com/go/getactivated.
Click Offline Activation.
Sign in with your Adobe ID.
Enter your Request code and click Generate.
Write down the Response code.
Switch back to the offline computer.
Enter the Response Code and click Activate.
https://helpx.adobe.com/creative-suite/kb/serial-number-validation-launching-cs6.html