To get the loot packs from Twitch you have to be a prime or premium users. Twitch prime is include with Amazon Prime. Check out this link if you don’t have Amazon Prime to see what it offers and to get a 30 day free trial!
Free 30 day Trial Amazon Prime!
Twitch also has another exclusive membership that you can get and it offers a little more then Amazon Prime like ads free viewing and more.
So choose which membership is best for you then link your WoT account to your Twitch account and claim the loot pack. Go back to your game and in the store tab you’ll see the package there for you to claim.