Install and activate the add-in manually or using Jerome Briot's Install scripts or addins from GitHub app.
Open a drawing with a component heirarchy, navigate to the Tools panel of the Design workspace, and click the BOM Generator icon in the Michael Greene panel group.
When prompted, select a destination CSV file to export the BOM to.
The exported BOM will contain three columns (Part Number, Part Description and Quantity). Components which are actually subassemblies (those containing other components) are excluded from the export.