On 22nd of June 2016, Gmaps re-introduced their requirement that sites and apps using the GMaps service use an API key before maps can be rendered in a page.
As a result, when you first setup a new site in Jomres you will need to request a new free key from Google.
Visit the Get an API key page.
Next, click the Get a key button.
Next, if you haven't already, create a new project
Next, create a Browser key.
And then create your API credentials. At the next step Google will give you an API key that you can use on your Jomres site.
Finally, copy and paste this key into your Jomres website. Go to Site Configuration -> Misc tab. About halfway down you'll see a field that looks like
And that's it, you're done!