I have done this steps to activate UVI Workstation in Dorico:
(may be unnecessary:) copied UVIWorkstationVST.vst from /Library/Audio/Plug-ins/VST to ###myusername###/Library/Audio/Plug-ins/VST
Closed all music apps
pasted “UVIWorkstationVST” into /Applications/Dorico.app/Contents/Applications/VSTAudioEngine.app/Contents/Components/vst2whitelist.txt
relaunched Dorico
(in Play tab on the right pressed +
chose UVIWorkstationVST
pressed E)
it works now.