Under Linux the installation is done to /opt/gladius/1.2.13 . However lib3mf.so is not installed. I managed to work around this by setting LD_LIBRARY_PATH to point to:

export LD_LIBRARY_PATH=.../gladius/gladius/build_release/vcpkg_installed/x64-linux/lib/:$LD_LIBRARY_PATH

But the proper behavior is obviously to install all dependencies.