S2S Tracking URL, when is it called ?

Hi, I see in the doc https://unityads.unity3d.com/help/advertising/s2s-install-tracking that the tracking url is called "at impressions (or clicks)", is there a way to know in which case it is really called ?

 

Depends on campaign type. For questions about configuring campaigns as advertiser, please reach out to our advertiser team at adops@unity3d.com.

Thanks,
Rasmus

 

Ok thanks for the response.
It would be good to have a documentation explaining how the process works