Are you running a new M1-powered Apple silicon Mac? If so, you need to run Dorico under Rosetta. Consult the Dorico 4 Version History PDF (pages 51-52) or see here:
From the Dorico 4 Version History PDF:
Universal app on macOS
Dorico 4 is now a Universal app, which means that it runs natively on both Intel- powered Macs, and on the latest Apple silicon Macs, such as the M1 MacBook Pro, iMac and Mac mini. If you have an Apple silicon Mac, Dorico will run as a native application by default.
VST plug-ins. When running natively on Apple silicon, Dorico can only load VST plug-ins that can run natively as well: it is not possible for Dorico running natively t…