Zed-10 home setup

Hey All, got my hands on a Zed-10 recently.
My main question is regarding the setup - how am I able to send my PC’s sound to the mixer? I would like to listen to stuff from my PC and send them out via the mixer to my monitor speakers.
I have tried a Y-cable 3.5mm jack from my PC to 2x6.3mm jack monos, and plug those monos into ST-2 as inputs. Not working.
Also tried the USB connection, from my PC’s regular USB-B port to the Zed’s USB-A and that does not work either.
ST1 as input for my Pioneer RX1 works fine. Sending out via Main Mix Out L&R to Yamaha monitors. Using Windows 10.

I might be in the wrong here, looking for a bit of help. Thanks a lot.

On you computer does the ZED show up as a sound output device?

You also can not have anything plugged into the ST2 jacks, doing that will override
the USB playback input.

Computer was at fault: thanks to Windows, the new upgrade rendered my soundcard spaghetti - had to reinstall audio drivers to make the Zed appear. Works fine now