hi,
I read that it was a recent known issue with CMake 3.27 as reported here: 2556 – Changes to FindEXPAT in CMake 3.27 break Geant4PackageCache.cmake file.
The best solution suggested was to install Geant4 with the option -DGEANT4_INSTALL_PACKAGE_CACHE=OFF to disable the install of that file (Or to simply delete it from an existing install, which will not break anything).
Please, refer to the discussion [Issues Compiling a Geant4 Example on macOS: Incorrect Macro Invocation in Geant4PackageCache.cmake]
Please, also check whether you’ve installed all the required Software Required to Build Geant4.