Someone responds to your ad because the offer caught their attention. Use an ad trigger to continue with a relevant reply and, where supported, collect the details your team needs for the next step.
Check your ad access first
Have the intended ad account and ad ready. Selecting an ad in Flow Builder doesn't create or launch a campaign. For account connection requirements and the instant-automation setup, see the existing Meta Ads automation guide.
Configure the Flow Builder trigger
Choose Replies to an Ad.
Select the correct ad account, then the intended ad in the content picker.
Enable Trigger on ad DMs when the flow should respond to messages referred by that ad.
Set keyword rules for the incoming interaction you expect.
Add the reply and any supported information-collection steps.
Run Validate before activating the flow.
Test the journey from the ad
Use the intended interaction on the actual ad. An ordinary DM doesn't carry the same ad referral information and is not an equivalent test of ad-sourced messages.
If your ad is missing, check the selected ad account and Meta access. If the flow starts but the next step fails, check that branch separately.
Need to report an actual qualifying outcome? See Send a Meta conversion event. A reply or flow run alone isn't proof of conversion attribution.