It’s not going to work, and this is not a flaw in the UR824.
Many PC sound cards (Sound Blaster, etc) are designed for music, simple recording, gaming and video (movie) playback. Many of these same sound cards have dedicated 5.1 surround outputs. That being said, these same basic sound cards have built-in decoders for Dolby and DTS 5.1 sound tracks on a typical DVD. This allows you to pop in a DVD, watch it in Media Player (or other player), select the 5.1 Dolby/DTS sound track, and then the sound card “decodes” and plays the 5.1 surround sound audio. Since these sound cards are designed for entertainment purposes, they are very common.
But the UR824 is a professional multi-channel recording interface with high-end D-Pre’s and capable of recording at 24-bit 192 kHz. It doesn’t have a built in Dolby/DTS decoder because it’s not a device that’s designed for entertainment purposes. In addition, most (if not all) other audio interfaces do not have built-in decoders for the same reason (AVID, Presonus, MOTU, etc).