Marker clusters help maps with many locations be more digestible by grouping the icons together as a user zooms out.
How to turn on marker clusters for your map:
*Note this setting will only apply to maps using the Open Street Map (OSM) base map layer. It will only apply to single marker locations (not polygons or polymarkers).
1. When logged into the CMS, go to the options tab and turn the Marker Clusters setting to "On".
2. Save then Publish and check out the front end of your map to see the marker clusters in action!