Good morning again Bill.
Yes, using apt to install cmake worked.
I moved the package from the RPI 4 to the RPI Zero using a memory stick (had not occurred to me that they can be read by the RPI OS when I previously used it on Windows machines).
wsjtx is now installed on the RPI Zero W2 and opens without errors - it even has the wsjtx icon installed.

Gary, I am not a software professional but a mere ham who likes to tinker. To learn more just use your search engine of choice - you can eventually find answers to most of your questions about Linux, Raspian OS, Debian, Windows operating systems as you need. And sometimes there is someone like Bill who can provide the snippet of guidance to push you forward.

I apologize to those who found this thread not of interest in this forum, but maybe someone else trying to build wsjtx on the RPI Zero want use his time as I have.

Happy Thanksgiving to those in the US.
Bill, again, thanks for your help and all you and the team have done in perfecting wsjtx for us weak signal hams!

Edd - KD5M