The plugin is a modified extended version of the Advanced Custom Fields: Coordinates made by Stupid Studio and is found here:
This software is licensed under the GNU General Public License version 3. See
gpl.txt included with this software for more detail.
The plugin relies on the Google Maps API. It does not use an API-key and is
therefore operating under the restrictions of the free Google Maps API,
which should be plenty for most backend usage.
When you create a new custom field with ACF, set the field type to
Multiple Coordinates map. Now the coordinates chooser should show up when you edit
a post with your custom fields.
The tool add a point on each click on the map. To remove the point you select the “Remove Coordinate” button and click a point.
You can also show the points as a Polygon on the map with the “Show area on map” button and show the actual coordinates in a semi-colon
separated list with the “Show coordinates” button. The search field is only there to quickly take you to different places on the map. Not
to add the actual points.
To get the coordinates data in your frontend, simply request the field value
and in return you get the coordinates in a latitude, longitude array and the zoom as in the sample below.
<?php $values = get_field('*****FIELD_NAME*****'); print_r($values); /* which will give you an array like the following sample Array ( [coords] => Array (  => Array ( [lat] => 57.156363766336 [lng] => 16.364327427978 )  => Array ( [lat] => 57.159612809986 [lng] => 16.370315551758 ) ) [zoom] => 13 ) */ ?>