There are two kinds of data that are associated with region maps.
Tiles (image)
Geojson (join your dataset with GeoJSON.)
To load Tiles, you can either upgrade to OpenSearch or use some of the WMS that are suggested here.
To include your own Geojson, you can include this setting (map.regionmap.layers.url) in your kibana/dashboard settings. Please check here for more information regarding region map settings,