The ADM and JDM Tails both come with a short harness that plugs into the factory main wiring harness...
SO...
When I installed my JDM tails... I removed the two rear lights... and the bulbs... and the short harness (One Per Side).....
then...
Installed the two new lights, the bulbs that came with them and the short harness that plugged directly into the car...
difference being yours were used and already on a car so the bulbs were included.. the CS ones are new and the bulbs do not come with