Does FreeNow also pick up at the T5 parking garage? At what point do you push the button to order the car?

EDIT:
Heathrow Terminal 5:

• Exit Arrivals.
• Take the exit to the right hand side of Costa Coffee.
• Follow Short Stay Car Park signs through two sets of double doors.
• Take the lift up to the short stay car park (Level 2).
• Pick-up point is to the right when you come out of the lifts, in front Row F.