Hmm, I don't remember my setup exactly, but I thought there was a way to manually add a new account for withdrawal, of course, you'd be entering account number, which is sort of like a password. But I'm sure they have to handle transfers from old-school banks that don't have all these fintech connections, perhaps their support could help, I'm not totally sure sorry!
Amusingly I got it to accept the ABA routing but then they recognize the ABA and force me to login.
I just don't want to type in my other bank's credentials into Wealthfront. I'm sure they know I don't but won't let me avoid it. So I'll continue to avoid them.