I assume that "register" means that the register() function in the eos crowdsale contract has been called by the account that holds the EOS ERC20 tokens, and that a public key has been stored in the crowdsale contract.
I'm sure you're aware of this, but you should encourage people to update their PK with EOS.io (re-register a key pair) after your airdrop for security reasons.
RE: Evolution Airdrop - May 10th