A Postback is an action taken by an interactive webpage, when the entire page and its contents are sent to the server for processing some information and then, the server posts the same page back to the browser.
So you need to provide your advertiser with your global postback.
You can find your global postback at offer settings
Take it and send it to your advertiser.
If you still have any questions, you can ask them in comments or contact our support team