They compromised the official Instagram account then phished its followers for their NFTs.
The attacker seized control of the BAYC Instagram account and sent a phishing post that many followers were fooled into clicking on, connecting their crypto wallets to the hacker’s “smart contract” – a mechanism for implementing a crypto transaction. That enabled the attacker to steal the assets held in the wallets, seizing control of four Bored Apes, as well as a host of other NFTs with an estimated total value of $3m.
They compromised the official Instagram account then phished its followers for their NFTs.
https://www.theguardian.com/technology/2022/apr/26/bored-ape-yacht-club-nft-hack-theft-art-simian-oblivion