How does this Whitelist solution work?

I was looking at Hape Prime's NFT smart contract and I am wondering how they executed their whitelisting. Their mint function in the contract can only be called by "onlyMinter" which is an address that is set by the updateMinter function that can only be called by the owner of the contract. I understand how it works but they whitelisted 8k people how did they automate and have such a smooth whitelist?

Etherscan of Hape Prime:

I think The Hape Prime contract(name as NFT Contract) doesn't manage whitelist, it is the caller contract(name as Airdrop Contract)'s work.
when open whitelist day, user can register their wallet address to Airdrop contract. in open mint day, the whitelisted user can mint NFT. NFT Contract's onlyMinter is Airdrop contract address. Airdrop contract must provide a function which will call NFT contract's mint function.