Moving to "Apple"

[Ralph6410]

Thanks to all that took the time to assist. I have finally won. Not sure where my problems started.. I think.. the solution came from ejecting the installation program from the finder program. I was previously ejecting from the desktop. Then, the Google came to my rescue in dealing with the “profile not found” error message. Evidently one can get to the profile manager without TB. From there I was able to see where the profiles are stored.. And how to delete the 18 failed attempts.

So from the profile manager I made a working default copy. Then created a new profile, renamed and moved to the appropriate folder the profiles from my Windows PC. Ensured it worked Several times.. then back to the profile manager and made the proper copy the default.

Perhaps this will help as well, how to start your profile manager without TB running
Copied from someplace..

Close the application completely and make sure that it is not running in the background. Assuming the program is installed in the "Applications" folder, launch Terminal ("Applications -> Utilities -> Terminal") and enter the command starting with / after the prompt in Terminal:
/Applications/Thunderbird.app/Contents/MacOS/thunderbird -profilemanager

Thanks again... for the forum, and those that help

[Anonymosity]

First of all ALL applications are in the Applications folder on the computer; they are not in user specific accounts.

Does that strictly apply now with MacOS Big Sur? With Sierra, I have a lot of applications in subdirectories in an Applications folder that I created in my standard account. It is easier to find things if they are categorized.