To use factor, you may need to add the $APPDIR/factor directory
to your PATH environment variable, e.g. (for Bash shell):
export PATH=$APPDIR/factor:"$PATH"
factor is built for Intel macOS and so requires Rosetta 2 to be installed.
You can install Rosetta 2 with:
softwareupdate --install-rosetta --agree-to-license
Note that it is very difficult to remove Rosetta 2 once it is installed.