Boot Camp Assistant will detect your Windows ISO.
Run BootCamp64.msi (for 64-bit installs) or specific .exe installers like AppleiSightInstaller.exe . bootcamp 40 4033 windows 10 install
: Many users report that Boot Camp Assistant fails to download the support software directly, often returning generic errors about saving to the selected drive. Apple Support Community Common Installation Errors and Fixes Boot Camp Assistant will detect your Windows ISO