You have to create your own Google Maps API key to use Google Maps widget.
The following tutorial explains how to get your API Key in an easy way: How to get Google Maps API Key.
Please, copy and paste your key in the field below. To manage your keys, please, go to Google Cloud Platform Console.
Don't forget to secure your key after creating it.
Your Google Maps API Key was configured incorrectly :(
Double check the tutorial, especially the following:
Includes: Maps JavaScript API, Geocoding API, Directions API
Check that you have added a correct website domain, also note that your widget may be wrapped with iframe with a different url/domain.