Hi Aya,
The clang binaries you downloaded should contain everything that is needed (if I remember correctly).
When installing clang, did you choose to add it to the PATH environment variable?
If not you will add -DLLVM_DIR=install/dir/lib/cmake/llvm to your CMake commandline for C-Reduce. Please double check the path I typed it from memory.
Regards,
Moritz
