If someone asks you to send your money for the airdrop, this is fraud. The very meaning of airdrop is the free distribution of tokens. To receive them you may need to either fill out the form or register in the whitelist.
But do not send any money to anyone, do not give your passwords and specify not your main e-mail, as many projects are fraud. You will receive a lot of useless spam messages. Like "You won something - send us money and get a prize", "only you are offered a closed sale, send money and get a 100% bonus."
Do not believe this ever.