You might need to check with Questyle to see if they support ALSA (communication protocol for Linux based boxes like Nucleus). I see they have all kinds of Windows drivers and support macOS. But there is no mention of Linux support. That alone, isn’t unusual.
Many/most DACs get along fine with ALSA, but some require Windows drivers or macOS.
There is this on Roon 
Nucleus and Questyle CMA-600i issue