Huh? You can't change a pdf file to be a .tax file. And not the other way around either. You need the actual .tax2020 file from the program.
You need to use finder and find the 2020 tax file. I don't know Mac very well but My friend has a Mac and I had to hunt for her 2020 file to transfer. It doesn't matter if you installed from the CD or from the download. It's the same program.
How to find tax files on Mac
https://ttlc.intuit.com/questions/1901659-find-your-tax-data-file-in-mac
