Your midi routing and audio routing are completely independent. You can sync your stuff however you like (well, in the order you need for everything to work!) and send audio wherever you want.
My idea of feeding the loop station input from the aux bus is that with an aux you can send any amount of signal from any channel to the bus. that way you’ll have independent control of the channel level and the amount going to the loop station. I’d plug all my inputs into the desk (A4 on two channels, AR on two channels with the option to send individual outs to separate mixer channels and the OP 1 into two channels) that way you’ve got complete control of all your outputs and you can set up a sub mix via the channel aux sends as well as having your main mix. It means you can send just one source or a mix of sources to the loopstation and then change what you send for the next part with your sub mix. It’s all about flexibility. Why compromise that flexibility by plugging directly into the loopstation when you’ve got a lovely mixer with longer faders and more routing options!
I’d plug my monitors into the control room output or whatever it’s called on your desk. Plug the loopstation output into another pair of channels then you should be able to use the pre fade aux send to route channel audio to the aux bus. If you turn down the fader for the channel and turn up the channel for the loopstation you should hear the signal back via the loopstation output. Turn up the aux send of that channel and you’ll hear it get louder at the RC output. Repeat for your other channels. Obviously don’t send any of the RC channel aux to the bus else you’ll, get a feedback loop. So know you should be monitoring the mix of what the RC will record when you hit the pedal. Don’t forget if you’re not sendin* stuff to the RC you just turn down that’s channels aux send and push up its fader. Now you’re mixing those channels with the output of the RC. So for example you might have the AR playing on ch 1&2 with nothing going to the RC. Ch 3&4 are A4 and have faders down and auxs turned up so they’re hitting the RC. The RC faders are up and auxes down. You can now record a loop on the RC of A4 sounds while the AR is happily keeping the beat going.
This is just one example. You can set up your routing however works best for you and how you find your workflow evolving. No one can tell you how to do that bit but the beauty of having the mixer is you get that flexibility.
If I was you I’d have a good read of the manual for your mixer. Learn what you can do with pre and post fade auxes, sub groups/mixes etc. It’s really not complicated; if you can read and can follow a line on a diagram you can see it. Once you understand what you can do then you can decide how best to set up so you can do everything you want to.