Multiple VSTs with UR824

I’m trying to run multiple VST instruments simultaneously with the UR824, but when I try and open the 2nd one I get an error that says the audio device cannot be opened. Specifically, I’m using the Arturia V collection, and want to be able to play keyboard 1 through VST 1 and keyboard 2 through VST 2, etc., through different midi channels. Is there any way to do this? It seems the Steinberg driver cannot be shared across VSTs. I tried ASIO4ALL but couldn’t get that working either.