So I've uploaded about 28,000 photos onto the cloud through Lightroom CC. I think that I'd prefer to use Lightroom Classic. Is it possible to switch to Classic and simply use the cloud storage that I've already establish (and if so how?), or do I need to have a local copy on my hard drive.
If you choose to switch to Lightroom Classic then you could synchronize with your Lightroom (for the cloud) and that would download copies of all those images to your computer. Lightroom Classic is computer-based, but allows you to share collections of smart previews with Lightroom (for the cloud). There is no Lightroom CC anymore. Lightroom Classic is the computer-based version and Lightroom is the cloud-based version. It is not possible, using Lightroom Classic, to simply access and use a cloud collection. That is not the function of that program.