To open Alien Worlds NFT packs, please go to the unboxing site: https://unbox.alienworlds.io/inventory/packs
After you login with your wax wallet at the unboxing site, you will then see the packs in your inventory. You can then open them using this site too.
Note: Please make sure you have enough WAX staked to CPU on your wallet, as well as enough RAM on your wallet. Otherwise you will get an error if you attempt to open a pack saying "Intermediate value not iterable". To learn how to stake resources to your WAX wallet, please follow this article: How Do I Stake WAX to CPU?