Ah, so that's similar to users having to be in the audio group (or another group with elevated realtime scheduling privileges) to be able to run jack properly. Well, in ubuntu, if you install qjackctl, you are lead through a wizzard that makes the necessary settings for you. I am not sure if this is a feature of the qjackctl install, or if ubuntu does this. But this is not very reliable (and likely not trivial to implement in a robust way), and if it fails, a user who doesn't understand what is required has no idea how to fix things.
How about this:
- on linux we could make cmake produce a infotext that states that further configuration is required to make HID work, referencing the linux readme
- you add a brief text to the Linux readme that explains the logic and the steps required