I have a feeling that the error message you are seeing on start-up is related to a shared Steinberg component installed by another application that is not compatible with Dorico 4 and the new licensing system. I don’t know where the location for these shared components is on Windows, but perhaps have a look in C:\Program Files\Common Files\Steinberg and see if there are any shared components for things like EUCON or Groove Agent SE in there that you could temporarily move out of the way.