The DLC has a bunch of regional restriction
This key is not available in the following countries: BD, MN, VE, BN, BO, JP, BT, HK, BR, FK, TL, LA, TW, PY, LK, NZ, KP, TH, PE, NP, PK, PH, CO, CN, CL, CC, CA, EC, GF, CX, AU, GY, IO, VN, ID, UY, MV, MM, SG, MO, KH, US, KR, AR, SR, MY, MX.

Gifting to anyone having the base game that still needs it