I did like 4 offers and never got any AP coins, the first one I paid with my cellphone, I even submitted ticket but nothing happened, not even a reply email. I tried again with 3 free offers in total after that issue but still never got any AP. Maybe because I never put my ID at the end of the URL but... I just read this, that instruction is not displayed on aeria offers page, so I would call it a scam of time or something like that.
Also, I'm user from another country, and I think they should add offers for people all around the globe because thats usually where users can not buy AP, not always USA or Germany.