To summarise my problem on the mac. My system is Mac OS Big Sur. First of all, I followed the tutorial and got a bad CPU type in executable: /usr/local/Trolltech/Qt-4.7.1/bin/qmake with the pre-compiled qt 4.7.1 (I don't know if this has any effect on the subsequent process). So I abandoned the pre-compiled qt and downloaded qt4 to compile it myself, but found that I couldn't install it. I ended up using qt5, and with some changes I was able to compile the main program, but not the plugins.

Because the plugin was written using qt4, some of the writing of the qt5 plugin has been changed. I think to use the plugin on qt5, the code needs to be upgraded.