As I understand it, someone may correct me, there is no available fitting on the Captur to take front to back roof bars.
The standard Renault, and other makes provide side to side roof bars that fit into a socket under the roof ridge in each door frame.You can see thisby opening each door, and looking up towards the roof edge just under the rim of the door.
The socket takes a pin and the feet of the roof bars sit on the roof. Not near the plastic front to back trim.
I know this may disappoint, but the Clio and Captur work that way.