/kit: Allows you to retrieve a defined set of items, called a kit, by its name.
essentials.kit Allows access to the kit command.
essentials.kit.<kitname> Where <kitname> is the name of an existing kit that a player has access to.
essentials.kit.* Allows access to all created kits.
/<command> [kit name]
You have to manually add it to the config then do /essentials reload. If you want you can give them access to the kit through permissions I think this is the permission essentials.kit.kitname . That should give them access to that kit.