Demo https://bonfork.com/preview/deerhurst-preview
To get an API key: Go to the Google Cloud Platform Console. Click the project drop-down and select or create the project for which you want to add an API key. Click the menu button and select APIs & Services > Credentials. On the Credentials page, click Create credentials > API key. ... Click Close.
You can find script tag for map at the end of the body tag.Between key word and ampersand sign paste the key you copied.