There is no add on store in Home Assistant core on Docker. So there is no HACS as far as I know.

If you have little experience with HA it is best to have the front-end available allthough it is possible to use any of the three parts seperately and it might suit your needs it takes some reseach to get from A to B. Since this is probably not your only challenge I would advise to ask the question in the more generic forum because I personally have no experience with it if you only run HA Core. Maybe someone else who might read this?