You are supposed to receive these certificates upon check-in (according to the Terms of the promotion). I have been handed these automatically at check-in except at the New York Marriott Eastside where I have had to ask for them each and every time. Once the front desk manager didn't even have them but they were delivered the following morning. Keep in mind that you can get upto $100 in these for a stay (2 nights or more). If you have to ask for them, then refer to them as "Bonus Bucks" as the employees I have interacted with so far seemed to be clueless when I said certificate, cash, voucher, etc but immediately understood when I mentioned Bonus Bucks.