Better to do away with the entire concept of downloading and running a shell script like that, and use distro native packages instead. It’s not hard to create DEB or RPM packages, ebuilds aren’t too bad either, and it sounds like AUR packages are managable too.
The entire concept of blindly downloading a script, running it as root, and hoping that, in the best case, it’d install the version of the software you want is a bit crazy. If the upstream developers refuse to provide packages, please, at least, provide a tarball.
Fair, that maybe came across harsher than I meant. Refusing to provide packages because you don’t use the system is fine, but please provide a tarball that I can unpack, rather than some dodgy script that has to try to work with the differences in those ststems anyway.