Surround soud on Primo via SPDIF

Hello, I am trying to play surround audio via the SPDIF output of Primo without success.

For example, I am using these files that tests all the 5 channels of a surround setup.
The files can be dowloaded in 2 formats:

When I play these files on my macbook pro via HDMI output (usb c to HDMI converter and HDMI cable going to the surround processor), the test sounds and voice come distinctively from the 5 different speakers

When I play the same files from my Primo (external HD) and SPDIF this is not the case.
In other words, my surround processor (Integra DTC-1) does not recognize the same files as multichannel when playid from Primo, while it does when played from my macbook

Any experience with surround audio and Primo?