Thanks all around for bringing this project forward. We’ve had some vital questions on the Cardano Forum about how owners of Cardano addresses that weren’t created through wallets can claim the airdrop:
Our understanding so far is that only a dApp will be provided for the wallets of eligible addresses to connect and present their claim. If this is true, it greatly disadvantages Cardano stake pool owners who have the bulk of their ada holdings in (and therefore significant Midnight claims from) addresses created by this standard method, rather than a wallet app & mnemonic:
https://developers.cardano.org/docs/get-started/cardano-cli/get-started/#generate-a-stake-key-pair
These addresses have been the canonical means of establishing a mainnet Cardano stake pool pledge for 5 years and therefore will collectively have a huge amount of ada stored in them, forming a significant fraction of the Cardano allocation for the Midnight airdrop… but we have no assurance that the tooling for the airdrop will support claims from these addresses. 
There could also be a significant security problem with these addresses & claims. The only known workaround for such a tooling deficiency would be to import the private payment keys for these addresses into Eternl wallet so they can interact with the claims dApp:
… but then the imported private key would have to exist on an Internet connected machine (since that wallet would have to be synced to use the dApp) without the rigorous safeguards that protect the private keys in the memory & data storage of wallet apps. In short: the more valuable the Midnight claim from our Cardano pool pledge, the greater our potential loss from our entire ada holdings. 
Cardano pool operators have generally kept these keys inside an Air Gap environment such as described here where they prepare and sign transactions. As the author of these instructions I would happily work with the Midnight team to document any procedure Cardano operators can use to submit such claims for these otherwise vulnerable — or (I pray not) currently ineligible — addresses.