Just saw your post you were able to download the .tax file? From a Turbo Tax Online Account? Which one? For 2018 .tax2018 or 2019 .tax2019?
Ok. You can't transfer a .tax2018 into an existing 2019 return. You would have to start a brand new 2019 return to transfer into. Go up to File-New.
If you are trying to open a .tax file you need to use the same year program. But The first thing to do before you open your tax return .tax file is to update the program and install any state programs you had. Then open your file. So you first might need to start a fake return to be able to download the state program (go to FILE - NEW).
