I might have missed something, but this should be pretty straight forward. I’m not a Cubase user, but in Studio One (and I believe all other DAWS) ,if you have all the Scaler functions turned off, including no instrument selected and no sections bound, you will get a direct pass through from you controller to your VST.
Try this…
When you have your strings vst working using Scaler, clear Scalers state (click logo), play some notes on your keyboard and you should hear just your notes played by your strings. You can turn on an instrument for a basic layered sound or you can turn on different perform and timing features and explore.
If it is more of a MIDI effect issue, you might get some ideas on this thread.
Good luck