From SD:
"Q) Is this for android device only?
A) No, you should be able to do it online just by clicking get app below:
http://www.amazon.com/dp/B00YD2DD..._TE_M1T1DP(Charlie Brown Christmas)
I got an error that my devices don't support it - but i hit continue and got the promotional credit a minute after the $0 order email came through.
No downloading apps or installing the app store. Nowhere on the page does it say this promo, it just worked."