The 20 word seed phrase is not BIP39 mnemonic seed phrase, better to make use of wallet ID and password so far you have both.
Althought i already know wallet identifier its password.
All you need to do is to use your wallet ID and password to loginHe will need to confirm ownership of the account using an email address and confirmation link. I think, without access to this email, he can't use a connected wallet.
OP, have you tried to access using the android app?