The AVX (or AVX2/AVX512) option can indeed cause compatibility issues with old processors. Since the object files you are using for compilation were built with AVX2 enabled, there is no way to remove that option and make those files work on processors without AVX support.

However, for this exact reason, we also provide object files compiled without AVX enabled. You should download the appropriate version of the distribution from the CRYSTAL Solutions website (should be named CRYSTAL23 - Precompiled object files for parallel version no avx2) and compile it using the same .inc file you provided.

Let me know if you manage to do it.