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.
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