If you are a nonresident alien, you cannot use TurboTax to file your tax return.
If you are a U.S. citizen or resident alien, the mailing address that you enter in your tax return has to be your current address. That might not be the same as where you lived in 2018. If your current address is not in the U.S., delete all the address information that you entered. Just above the space for street address there is a pull-down list that says "U.S. Address." Click the little arrow to open the list, and select Foreign Address. Then you will be able to enter your current foreign address.
