All Voxel Busters Plugins will be inside Assets/Plugins/VoxelBusters folder. EssentialKit folder contains the plugin files related to this plugin.
Folder Structure for Cross Platform Essential Kit
When you are trying to upgrade the plugin, make sure your Essential Kit Settings under Plugins/VoxelBusters/EssentialKit/Resources is committed to version control or have a backup.
All modules within the plugin uses assembly definition files(.asmdef). So these won't affect any of your project compilation times!