Most probably you are not using Google Maps API key, API returns the following error
"This service requires an API key. For more information on authentication and Google Maps Javascript API services please see: https://developers.google.com/maps/documentation/javascript/get-api-key",
Please collect 2 API keys (Browser type and Server type) and add those in Backend -> Settings -> Maps settings. For the API keys, several APIs like Geolocation API, Geocoding API, Distance API, Javascript API etc have to be enabled.
FYI, you are still using old booking form, this design is already deprecated and we will not provide any support for this. Please switch to new design, for that you have to choose Design 2 in Backend -> Settings -> Design settings.
Hope this helps
Ronniee