Online and Desktop are different and don't sync. But you can transfer from last year Desktop into the Online version. You need to have the .tax2020 file on your computer. You don't use the pdf.
If you used the Desktop program last year here’s How to transfer into the Online version. You need to have the prior year .tax2020 file on your computer. Expand the link if you used the CD/download last year........
https://ttlc.intuit.com/community/entering-importing/help/how-do-i-transfer-last-year-s-return-into-...
Do you have the .tax2020 file? If you can't find it, Here's an idea. Do you still have 2020 installed? Try opening 2020 program and see if you can get your 2020 return to show up in it. Go to FILE - OPEN. Then save it again with a name and place you can find. Go to File - Save As.
If you used the Desktop program before you may not like the online version. It has less features and no Forms Mode. You can only do 1 return. Your return is only saved online so be sure to save both the .tax2020 data file and the pdf file to your computer when you are done. In case you need to amend in the future or if you need a copy to get a loan or something. You might not be able to access your online return when you need a copy.
