Radarr needs functionality that is more specialized than most apps so there's special instructions and edge cases on all three platforms. But the Linux version is significantly more complicated because Linux doesn't provide as many out of the box tools for installation that works across all distributions like Windows or Mac.
I mean I'd just use containers (e.g. Docker) for it with a reverse proxy (also container). But I also don't think this is software which you're supposed to run on a System 76 laptop. You're supposed to run it on a 24/7 machine, a server. Could be a Raspberry Pi (if you can get hold of one :P).
Radarr needs functionality that is more specialized than most apps so there's special instructions and edge cases on all three platforms. But the Linux version is significantly more complicated because Linux doesn't provide as many out of the box tools for installation that works across all distributions like Windows or Mac.