Routing Issues with live recording

So I’m trying to set a live recording using the Xair18. I manage to get the input signal of mics and I’m trying to get into ardour a signal of my main mix (main LR) back to ardour to record it, but I can’t workout how to set this signals in Ardour, I just can’t find it, I believe it’s something to do with the routing (?) maybe?
I’m using Ardour 5 in a Mac.

Without knowing the details of the Xair18 … hardware I/O shows up in ardour as a set of ports named “system:in_N” and “system:out_N” (named this way so they are hardware independent).

You need to know which channels the Xair18 sends its main L/R mix on, and connect the input(s) of the track(s) to those channels. So if it sends the main L/R mix on e.g. channels 19 and 20, your tracks need to be connected to system:in_19 and system:in_20. Make sure you also disconnect them from any existing inputs they are using, since by default Ardour will automatically have wired them up in its best-guess-at-what-you-want arrangement.