That is the most important part if you want the turret to progress. On top of the ram is a piece of black plastic with a screw (auto index clamp) in it.
Undo the screw and pop the "little black piece" aka "square ratchet"
Now if you are loading pistol or 223 slide the Square Index rod in the the top of the auto index clamp, then place the turret into the top of the press and wiggle it till it all fits. To adjust the indexing follow the instructions with the press or visit Lee's website.
If you are loading larger rifle rds, don't use the square ratchet rod as it will index to soon and jam the case on the die.
A useful site for Lee presses
The Load Master Zone - reloading with Lee presses - videos and forums