Dorico 3 sound engine not working 'playback template not installed'

Dorico won’t play back with sound, no matter what i try. It keeps telling me 'This project references a Playback Template playbacktemplate.hsse that is not installed on this system. I reïnstalled both Dorico and the Sound library, but with no result… What should i do, I desperately need it to work!

Please create a new project from piano template, then do Help > Create Diagnostic Report.
That creates a zip file on your desktop, please attach that here.

Also, please run the Steinberg Library Manager (should get installed together with Dorico).
What does that program say, which libraries are installed. Maybe post a screenshot.