I finally resolved this problem on my MAC by following the uninstall and reinstall guidance at the following web page:
https://ttlc.intuit.com/community/installing/help/remove-uninstall-turbotax-for-mac/00/26050
This guidance removes all traces of older versions of TurboTax from the library directories on your computer. I found files from every version of the software going back to 2012 when I purchased my last MAC.
Prior to entering the activation code, I also disabled my virus protection software and the firewalls on my computer and DSL modem.
