Actually correcting the problem would be more helpful than an article addressing the problem.
In any event, as I edited my original post to reflect, I used another computer to copy the TurboTax Install CD files to a USB drive and used that to install TurboTax 2021 Home and Business on my primary computer (which does not have a CD/DVD drive). Doing that, I was able to install and activate TT 2021. It also updated the TT files, so presumably TT is working.
I sure hope that TT 2021 has fixed the activation issue that plagued the 2019 and 2020 editions, where if you changed your computer's hardware in any way, adding or removing a USB drive or other USB device, TT would think it had not been activated and would ask for a new code. After going through many codes and calls to Customer Service in 2019, I learned with 2020 to make sure to have nothing attached to my computer when installing TT and if the activation screen ever came up, to disconnect all USB devices. 2019 and 2020 even ask for activation codes if I connect a card reader (with no cards in it) to my computer.
