I already paid my 2024 taxes, but somehow never filed. What do I do?

Go through the steps of the FILE section.   If you already paid the federal tax due, when the software asks how you will pay, just say you will mail a check.  You do not really have to do that, but it gets you past the question.  You have to go all the way to a big orange button that says "Transmit my returns now" in order to e-file.   Until you click that button you have not e-filed.

When you e-file your federal return you will receive two emails from TurboTax.  The first one will say that your return was submitted.  The second email will tell you if your federal return was accepted or rejected.  If you e-filed a state return, there will be a third email to tell you if the state accepted or rejected your state return.