The easiest way is probably to study the 2 demo views that ship with the app.
The module supports drilldown in 2 ways:
Custom field drilldown
When using the module in a custom dashboard, you can specify a drilldown field. All unique field values are then collected per location. When a marker or Cluster is clicked, those values are automatically combined/formatted in the form of
((<drilldown_field>=<value1>) OR (<drilldown_fields>=<value2) OR ...)
This partitial search string will be propagated to downstream modules as a setting ( maps.drilldown ) an can be leveraged using eg. a stringreplace intention.
Automatic drilldown
When there is no drilldown_field specified the drilldown can only happen when a marker is clicked that represents a single location (ie. not when a cluster is clicked). So when a marker with 2 or more locations (distinct _geo values) is clicked, the maps view will be centered on the cluster location and the zoom level will be incremented. In the case of a single location the module will propagate the setting maps.click containing the _geo value. This setting can be used in all kinds of intentions (stringreplace, addterm, etc) or using the GeoDrilldown Module which will essentially append | search _geo=<value> to the search string.
... View more