UPDATE: I've found the wallet.aes.json file of the wallet and was able to decrypt it with the same password that the site claims is the wrong one.
What should I do next? Should I "import" it (using this link - https://login.blockchain.com/wallet/import-wallet)? It is already in their system, so maybe "importing" isn't the right thing to do.
Can I use this file to gain access to my wallet from another site, or is this file unique to blockchain.com?