"I sort of understand what you did in your screenshot above, but I have no idea how to duplicate it"

OK, NEW Screenshot. I installed GR5 on this computer to make it as simple as possible.
I realize that it's a pretty busy Screenshot, but easier than posting multiple Screenshots.

NOTES:

FCB1010 Track - MY MIDI Interface is called MIO. YOUR MIDI Interface is called Studio 24c. Where the Screenshot says MIO yours should say Studio 24c.
In YOUR Screenshot you're SENDING to your Interface. Set that to Guitar Rig5. Duplicate the FCB1010 Channel settings with those changes.
Make sure that the STUDIO PORT SETTINGS show YOUR Studio 24c where MINE show MIO.