I have not seen your door hardware but almost all track doors with rollers work the same way. The bottom rollers are adjusted up into the door and the top rollers are spring loaded. The door is fit into the frame and the bottom rollers
are adjusted down to raise the door and engage both top and bottom tracks. The door has to be adjusted just enough that the top rollers cant come out of the track but still need to have some spring compression left, otherwise the door will bind. If it is impossible to get the proper adjustment it means the floor or ceiling is not parallel enough with the other and the track may need to be shimmed.