If you are using a catalogue ad that pulls a dynamic website URL from your catalogue in your Commerce manager, you will not be able to add the UTMs directly to the Website URLs the way you can on a "Single Image/Video ad", so you need to add the UTM parameters to the 'URL Parameters' box in the Tracking section at the bottom of the ad:
When your products are automatically synced with FB, the website URLs are updated inside FB to include the URL parameters:
comet_source={{site_source_name}}&comet_ad_id={{ad.id}}&comet_placement={{placement}}
You can publish the ad, and you will be tracking accurately with Cometly!
Important: When you update your ad parameters in the URL parameters box, your ads will go back into review for a very short period of time. Updating URL parameters is not considered a significant ad edit so learning will not get reset on yours ads. Please see the Meta resource article that outlines what are considered significant edits that will reset learning.