To participate in airdrop you just sign up the form then do a few tasks then you will get your token soon but an airdrop that requires to send a small fee that is a scam for sure. Imagine if thousands people join this kind of airdrop then the scammers will be happy, we make them rich easily so avoid this kind of airdrop.
Yes, obviously any airdrop requiring participants to pay fees in order to receive tokens is scam. Some even try to hack participants by asking for private key when filling form, and some newbies who are ignorant fall prey to this.