How to combine webhooks and event subscription?

Hi, I'm new to qualtrics API. I want to build a web service that can send the survey response data out to another website.
I'm referring to this article. https://api.qualtrics.com/instructions/ZG9jOjg3NzY3MQ-retrieve-survey-responses-in-real-time, which tells me to create an event listener outside qualtrics(in the example is using python to build a simple listener), then create an event subscription to record this listener. And then, call this listener with webhooks "surveyengine.completedResponse.{SurveyID}", in order to retrieve the responseID. The last step is using this responseID and surveyID to get the actual response data.
Currently, I can create a listener and get a 200 response when I create the event subscription. The question is, I don't know how to implement the webhook surveyengine.completedResponse.{SurveyID} in a workflow of a survey? I assume we can only call the listener with a post request in the "task-webservice" in a workflow? But where should I put this webhook in the workflow of an actual survey?
I've also searched in the community, https://community.qualtrics.com/XMcommunity/discussion/15987/webhooks-and-web-listener-python-code-decoding-for-understanding this post showed some clues, but I still don't get it. Can someone help me out?