Google requires you to register an API key so that you can show Maps on the site. Please follow these steps to get the key:

Step 1: Login to your Google account and Go to this link https://console.developers.google.com

Step 2: Agree with Terms of Service if this is the first time you have gone to this link.

Step 3: Go to this link Google APIs , click on this one link of Google Maps JavaScript API  and choose Enable.

Besides, go to Google APIs , search for Google Place API Web Service  and click Enable

Step 4: Select an existed project or Create new, then click Continue.

Step 5:

♣ Choose HTTP referrers (websites) in Key restriction section

♣ Fill in your domain. You can use multiple domains, but one should match the current domain. For example, link of your site is https://www.jobmonster.com, you will enter *.jobmonster.com/*

Step 6: Click Create.

Step 7: Copy the API Key then paste into the setting above.

For more reference, you can see: Official Document, Google Blog