It did work for me, though, so maybe your situation is different from the one described here. But be sure to pick a location on your Mac for the downloads that is not restricted by Mac OS. That’s what actually causes this – In Catalina apps are required to ask permission to access the Downloads folder, and probably others. I created a temp/toontrack folder in my home directory and that worked.
Unfortunately I’m stuck on another gotcha, which is that Roland’s V-Drums MIDI driver isn’t yet compatible with Catalina. Good thing I only updated my travel laptop, not the one normally hooked up to the set. Sigh.
