You can install the addon like a normal WordPress plugin. The only requirement is that the Pro version of Interactive Geo Maps is also installed and active.
The option to populate your map is currently only available for Regions and Round Markers.
Once the addon is enabled, when creating or editing a map, the options to populate regions or markers from information from your different post types can be found in the ‘Other Data Sources’ option, as the screenshot below shows.
If you’re not seeing these options, make sure you have the ‘Other Data Sources’ option enabled, under Settings > Map Features, for both Regions and Markers.
The options are similar between regions and markers, the main difference being that for regions you need to have a field with the region name or ID and for the markers you need to have a field that stores your coordinates value.
Each individual map can only populate regions from a unique post type, but you can have different maps reading from different post types. You can also have in the same map the regions reading from a certain post type and the round markers from a different post type.