It wasn’t immediately obvious to me while following the installation wizard that the Add Cache Device UI is intended to be used one device at a time. In fact, since I didn’t want to RAM cache (too little RAM available), I spent some time trying to set a zero RAM cache (which it won’t allow), instead of just ignoring that default “Select Device” item, and moving straight on to a Flash drive.

It’s more intuitive when using the “Add.. ” button from the installed Control Panel, but I think the installation wizard could be clearer.