indeed, if you have upgraded to catalina, you will need to use the development version 1.5:
https://sourceforge.net/projects/scribus/files/scribus-devel/1.5.5/if you need the stable version 1.4 of scribus, it's indeed possible to use it in a virtual box with linux.
if you have not upgraded yet to catalina, check the compatibility for all software that you need.
that's the current state.
and it won't change: there will never be a 1.4 that works with catalina (but one day 1.5 will be come the new stable 1.6... if you know what i mean).
if you already know scribus (or have good DTP skills) and you're free to choose which version of scribus to use, then i would go for 1.5 on macos (warning: scribus 1.4 cannot read files that have been saved with 1.5!)
in all other cases, try both and see what you like better...
and i'm not aware of 1.4 having better better support than 1.5... as far as i know all the people giving (good) support for scribus have been using the development version for years.