Yes if you have the file ending in .tax2019, .tax2018, etc. you can open it in either the windows or Mac program. You need the same year program installed. And you can transfer the prior year .tax file into either program or into the Online version.
After you get the program installed the first thing to do before you open your tax return 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 TAX RETURN)
Then go to FILE -Open and find your return.
