Setup Decklink SDI 4K for 5.1 Monitoring in Adobe Premiere

Hey Folks. I don't get it... I try to output a 5.1 mix via HDMI (Multichannel PCM) from my MacOS Premiere timeline. In my world timeline track 1 mono should be channel 1 on my HDMI stream, track 2 mono on channel 2, ... Like editing to tape via SDI in olt times. But how!?
There are so many settings: audio preferences, audio hardware preferences, timeline track settings, 5.1 channel assgnment, multitrack and so on. The Decklink HDMI output is connected to my AVR.

Any ideas? Resolve works fine with the same hardware setup btw. But now I need it for Premiere.

So, my questions:

• How to setup preferences
• How to setup timeline
• How to setup track mixer

Thanks a lot!