Hi biuechocoo
On 22 June 2016 Google Geo Developers announced that Google Maps no longer supports keyless access to their API and that all API calls must now contain an API key.
This means that all new and existing users of WP Google Maps will now have to register on the Google API console in order to get a Google Maps Javascript API key. In the past, Google Maps allowed you to display a map without an API key but unfortunately from now on this will not be possible.
There are no costs involved with creating an API key however, as it has been in the past, you will be limited to 25 000 map requests per day.
For full documentation on how to create this API key, please visit https://www.wpgmaps.com/documentation/creating-a-google-maps-api-key or watch the video tutorial on Youtube (https://www.youtube.com/watch?v=OH98za14LNg)
The above documentation will also provide which services need to be enabled in your project for your maps to display as expected.
I hope this helps? If not, would you mind still sending me a link to your map so that I can look into this for you?