You need to download the .tax2019 file from online to open in the Desktop program.
First download the .tax file from the Online version,
https://ttlc.intuit.com/community/saving/help/how-do-i-save-my-turbotax-online-return-as-a-tax-data-...
Then see, How to Switch to Desktop,
https://ttlc.intuit.com/community/choosing-a-product/help/how-do-i-switch-from-turbotax-online-to-th...
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. So you first might need to start a fake return to be able to download the state program (go to FILE - New)
Then you just OPEN the .tax2019 file, go up to File-Open. You don't import or transfer it.
