The bass_dts.dll supplied by Steven appears to be the same as the one at
https://github.com/pudding-fox/BASS_DTS/releases/tag/0.2.1 , which despite the "last updated 3 days ago" still has a file date of 10/18/2022.
MusicBee WILL play 5.1 DTS files with the above DLL installed, I just tested a sample. I only have a stereo setup so can't test the 6 channel playback. I think the reason MB can't play the WAV file with the DTS content linked to by the OP (won't play here either) is due to the comment at the github release that:
"As of 0.2.0 this library is working as a BASS plugin. This means you only need to include bass_dts.dll with your application (with your other codecs, likely in the addon folder). One caviat is that BASS will prefer a built in codec if it finds a header, I have observed .dts files with
WAVE/RIFF headers that cause BASS to play the file as wav. As plugin codec association is only by file extension, I don't think there's a way to prevent this behaviour."