If anybody asks you to pay for the airdrop, it’s a scam. If somebody sends you a direct message (DM) telling you you need to pay for the airdrop, it’s a scam.
The only cost in our airdrop is the gas fee to claim your tokens (which you need to do on Optimism, so you’ll need to bridge some ETH over if you don’t have any). You can verify the token is legitimate by looking at the token address.