Dear Arash Papi

Please read the error. You are installing GROMACS 2021 which doesn't accept -DGMX=ON but you have to choose which GPU acceleration you want, as the error says, i.e., CUDA or OPENCL or SYCL. Read the documentation

https://manual.gromacs.org/documentation/2021/install-guide/index.html

If you want CUDA go with -DGMX=CUDA