Hi. This is my first post so please be gentle.

I'm making the model of the M18 Hellcat. I create the track following the steps in this video. When I got to 1:25 in the video, I saw a cube which seems to "drag" the chain with it when the cube moves on the track. I was unable to replicate the result. I managed to make the cube moves on the path but I don't know how to mate the cube with my track. Can anyone help me?

Part and assembly attached