The following instructions are based on a reddit comment of u/zolixes and cleaned up/modified by me.
- Arch Linux with kernel version 5.0.9
- Steam build
jenkins-steam-runtime-beta-release_0.20190320.2
(As seen from Help -> System Information -> Steam Runtime Version)
There is a file: /lib/udev/rules/99-steam-controller-perms.rules (if no rules related to steam are found install the steam-devices package and this file will appear).