FLOOR 49 Here we have three circular walkways and two rooms - SE and SW. Go SW to middle walkway and operate terminal No.2 once to turn SW room, then go thru SW room to outer walkway and head N. Along W side of the room observe for TC - toss moogle at it to get the item required by the terminal.
Loop around the outer walkway to reach the crystal gate - activate it to unlock AF300 Oerba, then return to AF200 Augusta Tower. Continue going N on outer walkway, operate the terminal once to turn SE room and go thru the room to reach middle walkway.
Now walk N and toss your view down towards NE. You'll spot a TC all the way down in the depths - aling your moogle throw properly and moogle grabs TYPE-C item from the TC. Return to F50.
FLOOR 50 Give the item to needy terminal for AF200 AUGUSTA TOWER FRAGMENT (03/04), then examine the third terminal in this room. This one wants to have TYPE-C item, also hidden somewhere on F49, which we already have. In return you get AF200 AUGUSTA TOWER FRAGMENT (04/04), and Access Card TYPE-13.
AF300 Augusta Tower
Board the lift on F15, and examine the control terminal... Now you can reach F13, which doesn't have anything interesting, except for having to go here for 100% map completion.
I don't know their proper english names yet, since I'm not that far. Currently hoarding CP in AF400 Academia.
The first complete English guide to Final Fantasy XIII-2 is here! http://www.gamefaqs.com/ps3/619315-final-fantasy-xiii-2/faqs/63553
You get the 13th floor access key from doing the Paradox Agent Type A, B, and C quests from the 50th floor of Augusta Tower. I didn't have any issue getting to the 13th floor once I got the key for it. Not sure why you guys are having issues... I just clicked on the elevator panel on the 15th floor and it said 13th floor access confirmed or something similar.