Hello,
https://developers.google.com/maps/documentation/javascript/tutorials/adding-a-google-map#step_3_get_an_api_key
You need edit the file wp-content/themes/legenda/contacts.php, find the line 171
<script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?sensor=false"></script> , replace the code with this
<script type="text/javascript" src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&sensor=false"></script>
, add your API key instead of “YOUR_API_KEY” text in the link.
Regards,
Rose Tyler.