According to Humble:
This key is not available in the countries listed below:
AR
BO
BR
BZ
CL
CN
CO
CR
DO
EC
GF
GT
GY
HN
HT
MX
NI
PA
PE
PY
SR
SV
UY
VE
(Pretty sure I got the region restricted part in the giveaway setup set correctly; figured I'd put this here anyway. Good luck!)