Hey @zbud! So, you just need to place the zillow api key in the required field in the WordPress IDX Theme API options. You will also need a google maps API key and have that added as well. Once both of those are in place, the widget/shortcode for the Home Valuation should work just fine!
If that is selected and saved and the home value is still not showing, send us an email and we will troubleshoot further, but, I suspect that is the issue because everything else is working as expected.