No problem. Can you say how got the Google Play promo?
You know, I have no idea
It is sent to my GMail account directly from Google, and that account is tied to Google Play (and other services), so I'd assume that's the entry point.
FWIW, back from December, through the end of January, I wound up getting 3 of these 50% off to own promos (and two $0.99 rentals), and they're good for any movie, sets, new releases (I think pre-orders were the only exclusion). It's nice because you click through from the email, auth into Google, then it stores them so you don't have to use it immediately. Then during the purchase process it will show the discount of an available promo (assuming oldest first), but it will also allow you to apply any you have (or none at all, like when the IP Man trilogy was $2.99, I opted not to use one).
I hadn't gotten one in a few weeks - I did use all the others I received - maybe I'm flagged as a "repeat consumer" or something