The problem of Google Maps plugin not working in website builder is usually caused by a missing API key in the brand on licenses page. To insert your API key, please take the following steps:

• Create your API key in Google console here
• Enable the following APIs for your key:
  • Maps Elevation API;
  • Maps JavaScript API;
  • Places API;
  • Geocoding API.
• Add the value of your API key into Site.pro configuration:
  • Navigate to My Licenses page;
  • expand your brand;
  • click on Plugin API keys link;
  • add your API key into field API Key of block Google Maps;
  • click Apply button in Plugin API keys dialog and Apply button in Brand dialog.

Make sure that your Google Maps API key in website builder installation is authorized and not restricted to be used for your website builder domain. You may also try to use another API key to check if this solves the problem.