No. It’s not a USB sound mixer. It’s an analog mixer with a built-in USB hub. The analog mixer qualifies as one “device” and anything else you plug in to the USB ports qualifies as a separate device. Audacity will only record from one device at a time.
You can add Windows software to record from multiple USB devices and I thought it got added to the wiki, but I can’t find it. Looking.
http://manual.audacityteam.org/o/man/faq_recording_how_to_s.html#twomics
Here it is:
https://forum.audacityteam.org/t/how-can-i-record-using-2-mics/34647/9
Koz