Of course you have to earn six figures to qualify for this "affordable" unit. A two-person household could earn a maximum, as of 2017, of $126,060. That means annual rent payments of $32,232 would represent 25.6% of income.
(Half the units in this building, as with 38 Sixth, have rents set at 160% of Area Median Income, or AMI, with household income up to 165% of AMI. That's decidedly middle-income, and a small slice of the city's population.)
Actually, all five two-bedroom apartments available at 535 Carlton now offer two months free, and the two one-bedroom apartments available offer 1.5 months free. That's up from the previous offer, just two weeks ago, of 1.5 months and 1 month, respectively.
However, StreetEasy's 535 Carlton overview page hasn't quite caught up in the reality, since only one unit, as shown in the screenshot below, has its effective rent listed, while the others have the official rent listed. So that anomaly reminds us that effective rent of $2,686 for a two-bedroom is awfully close to the listed rent of $2,680 for a one-bedroom.