I couldn't follow all that. You bought the Desktop download program? Then what? Did you get it installed and Activated? If you used the Desktop program last year you should have the tax file ending in .tax2019 on you computer, right? You can transfer that either the Desktop program or the Online version.
Then it sounds like you are trying to use the online version? Desktop and online are completely separate so you have to pay for online even if you already bought the Desktop program.
No you can not transfer into a return you already started. You would have to clear and start over to transfer from 2019. If you already started an online return you will have to clear it and start over to transfer. How to clear and start over
https://ttlc.intuit.com/community/using-turbotax/help/how-do-i-clear-and-start-over-in-turbotax-onli...
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.
