First, you need to access the popup editor page and navigate under "Targeting" > Then click on Create New Custom targeting rule (not available on the free plan).
AD MEDIUM- utm_medium
AD CAMPAIGN- utm_campaign
Example: User wants to trigger a Hello Bar popup on this page (with UTM param) http:// www.yoursite.com/pricing utm_source=active%20users&utm_medium=email&utm_campaign=feature%20launch&utm_content=bottom%20cta%20button
The ad source should be like this in Hello Bar.