Starting the MoveIt package requires that you have first setup your robot and environment as specified in the main README.
In simulation this is launched in two shells as follows:
roslaunch iiwa_gazebo iiwa_gazebo.launch controller:=PositionTrajectoryController
roslaunch iiwa_moveit demo.launch
Alternatively it can then be started on a real robot by activating the driver:=true
option:
roslaunch iiwa_moveit demo.launch driver:=true
Your robot will release brakes at startup of MoveIt.