Sorry if this is the wrong place, it's a Linux question but it's come about whilst trying to build my arr-Plex stack.

So, Linux (Debian) user accounts; What is best practice for running applications as their own UID? Why should I do that? and how can I avoid file permission errors.

I see advice such as "create a new system account called radar/sonarr/Plex". So I do that, and then find all my downloads are owned by qbittorrent user and it doesn't have permission to move them into my Plex library and Plex can't view them either.

All seems overcomplicated. Why can't I just run everything all with username 'Plex'?