I have an older computer (custom built and added to over the years), run Windows 10, and had this same issue. I purchased the download from Amazon. I installed and uninstalled at least 5 times. I downloaded twice (thinking there was a corrupted download).
Finally, after running the most recent install, I went directly to the program directory where I installed the application (for me: F:\Program Files(x86)\TurboTax\Deluxe 2020\32bit), I selected the TurboTax application (file type = Application) and then selected to "Run as administrator" (for me you get this option using the left-click button on the mouse, but I run a left-handed mouse).
Boom - the Activation screen loaded and I was able to enter my activation key from Amazon. Appears to be working now.
