How to set up an aggregate device with Rockville mixer and blue yeti mic for Adobe audition and riverside podcasting on Mac?

Hi! I am trying to connect a Rockville Mixer and Blue Yeti mic to my Mac. I am desiring to use it in Adobe Audition and via the Riverside Podcasting platform. I have played around with the settings in Audio MIDI Setup, but I am guessing that that is where the problem is. The Rockville Mixer and the Blue Yeti are connected via USB. Both work as singular devices, but when I setup the aggregate device in the MIDI setup, I must be doing something wrong.

To give some info, and to ask for the answer, the Rockville Mixer is an input/output device. I think I have tried setting up the aggregate device with all of the different channels but I would be willing to hear any advice. If you do have an answer, I would prefer it to be as detailed as possible, but am not adverse to asking follow-up questions.

Any help would be greatly appreciated,

Rob

[Re-Titled by Moderator]

Original Title: Question about setting up an Aggregate Device - Rockville Mixer and Blue Yeti Mic. Problem likely with Audio MIDI Settings, but any answers appreciated