Unable to download specific GROMACS version (for cutoff) using sudo apt install gromacs=<<version>>

GROMACS version: Irrelevant
GROMACS modification: No

I am trying to run a file with the deprecated “cutoff-scheme=group” setting for I am not fully sure yet how I can appropriately configure the file with the new cut-off scheme setting and I am specifically simulating water anyway.
I attempted to download an older gromacs version using the site’s guide, however, I could not run gmx commands after running the installation (even though the installation seems to have completed correctely as far as I can see).
So, I then tried to do it the simpler way by installing a specific gromacs version through sudo apt-get install gromacs=... but when I put in version names they generally do not work. The only one I managed to make work was the version listed – which is what you would expect (sudo apt show gromacs gives version “2020.1-1” but that …-1 is not appicable for any other versions, it seems).

I thought it might be better to just try and use and older version since I am not very confident in my ability to rewrite the grompp.mdp file - and I cannot make much sense of the explanations that I see - but everything I tried brought other challenges.