I filed for my return to be direct deposited, but it says “ready to mail”?

Where do you see "ready to mail"?  Is that what you see at the Tax Home of your Online TurboTax account?

If you see a status of "ready to mail" in your TurboTax account, that means that TurboTax thinks you intend to print, sign, and mail your return.   Did you choose to file by mail?  If so, TurboTax does not do the mailing. If that's how you want to file, then YOU have to do the mailing.

If you haven't actually mailed it, and want to switch to efile instead, we can tell you how to open your unfiled return back up and change filing methods.

BTW, direct deposit of a Federal refund is available for both efiled returns and mailed returns.  State choices can differ.