Show a popup to user is a very complex action and a number of steps are required to get everything working properly.

To begin, make sure you have Popup Maker installed.  Then you’ll want to start by creating your popup.

Step 1 – Creating the Popup

1. If you’re not familiar with Popup Maker, refer to very comprehensive Popup Maker documentation to build a popup.
2. Once you’ve created your popup, choose a trigger, as you normally would.  Typically you’ll want the popup to auto open:
   
3. You’ll probably also want to set a cookie on popup close so that the popup is only displayed to the user once.

Step 2 – Creating the Automator recipe

1. Create your new Automator recipe and give it a title.
2. Add the desired triggers that will show the popup to the user.
3. Create new Popup Maker action. Choose Display the Popup for a user.
4. Click the Popup box in the action and choose the popup you created above.
5. Save the Popup Maker action.  This will automatically add a new trigger to your popup.
6. Switch your trigger(s) and action(s) to live, and the recipe as well.

Once you’ve completed the above steps, your popup should have two triggers – “On Automator Recipe Completion”, which is added automatically when you create a Popup Maker action, and whatever trigger you picked in Step 1.

And that’s it! You now have a recipe that will show a popup to the user on completion.