When you enter Central Control Tower, there Is a warp to the left that takes you to 3 locations. You have to go to them 3 locations and reach the warp back to CCA. {BUTT, before going back, you have to press a terminal that Is the switch to unlock CCA, found generally around the warp back, or a room before the room with the warp back you have to repeat this process on each locations}
Also have In mind that those stages are hard for one person, unless you are well prepared :"L