This is odd; I just went back to Finale to update the audio files for several old works I just released on my Bandcamp site and it was fine (Finale itself; not so fine, but I figured out many workarounds to deal with lots of stuff that doesn't work or isn't reliably working). What happens if you click MIDI/Audio:Reassign Playback Sounds?

What does your configuration look like under Audio Units Banks & Effects? Is the ARIA player there in the dropdown list?

And it even works fine in Dorico (I'm now on version 6). I just proceeded to switch a recent work from NotePerformer to Garritan Personal Orchestra 5 using the ARIA player and it played back perfectly well. I'm not sure how your system is configured but here's how it is on my end:

Finale and Logic use Audio Units; Dorico uses VST3. It's odd that Logic should work, but not Finale. 

Do you have ARIA plug-ins in /Library/Audio/Plug-ins? (Audio Units are in "Components" folder; VST3 is in... well, VST3.)

If not, restore them from your backup from before you installed CPO.

Audio Units work well in Logic ProX and Dorico 6. Finale 27 doesn't see my Audio Units.
I restored the Audio Units in "Components" folder but still, Finale doesn't see any of these sounds.
This is really a nightmare and the help center is really not efficient (Zacharias).

MIDI/Audio:Reassign Playback Sounds makes an error message : no Plug-ins Audio Units