If you have any problem with Google Maps, please open console to see error message. You can do it e.g. by clicking F12 in Chrome: 

In this case the added key is not valid. Please create new one this way:

How to display Google Maps on my website? Creating a Google Maps API Key

The most popular problem with map is that added key do not have all Googlem Maps API key activated. Please make sure you added all 

  • Maps JavaScript API
  • Geocoding API
  • Places API