Hi @khangnb happy to help! There may not be a great way to do this based off of any dealstage change but I think this should work:
You should set your criteria to be that "Deal Stage was updated in the last 1 days" and allow for re-enrollment.
Then you should be able to add a workflow action to POST to your external URL. To add a webhook action from a workflow, you can click the plus button and choose the "Trigger a webhook" action. Here's how my workflow looks, which appears to work: