Hi @maryamma! GROMACS 2020 is not supported anymore, so we strongly recommend using a newer version which offers better performance and less bugs.
If you are sure you need GROMACS 2020.7, please follow the advise in this thread: Gromacs(2016)/Spack Compilation Fails- error: 'numeric_limits' is not a member of 'std'. This is a different issue from the one being discussed in this thread by others, which is related to a regression test location.