The release tarball ships its CMake package files under lib/, but onnxruntimeTargets.cmake resolves the library as <prefix>/lib64. Ubuntu is multiarch, so CMake does not search lib64 for packages and ld.so does not search /usr/local/lib64 at all, leaving find_package(onnxruntime) failing on a stock install. Keep the libraries in lib64, move only the package files to lib/cmake, and add lib64 to the linker path.