Your best bet to find specific instructions for your particular setup would be to search around for youtube videos and/or forum posts from people who have similar equipment.
Since you have the Devo 7 that does not have a USB port it becomes a bit more tricky. You will need to connect it via the trainer port instead.
On Windows that would be pretty easy using a software called Smartpropolus. I haven't been able to find a similar software for Linux.
(Devo 7E in combination with Deviationtx would be easier since that can act as a USB joystick)
You might also be able to use a universal 22-in-1 USB dongle such as this.
https://www.banggood.com/22-in-1-RC-Flight-Simulator-Cable-for-Realflight-G7-G6-...
Not sure if it works on Linux.
(You might also be able to connect it via a wireless USB dongle in combination with a receiver for the Devo 7, I wouldn't really recommend going down that path unless you are willing to do a lot of research though).
It might just be easier to get a USB dummy controller such as this:
https://www.banggood.com/Wholesale-Httpwww_banggood_comWholesale-6CH-G4-XTR5_0-R...
Not sure if that works on Linux either though. So in summary, I cannot give a definite answer for such specific and hmm shall we say tricky equipment. There are so many Linux distributions and variations, you need to try it on your own setup to know what will work for sure.