Are they forcing you to use the cloud-centric Lightroom, or do they also allow the use of the Lightroom Classic app? Lightroom Classic works with locally-stored images, so would probably suit you better.
However, if you are having to use the cloud-centric version, what's the problem with uploading the images to the cloud? Yes, you can pause cloud syncing so that all the images you add will remain on a local hard drive waiting for cloud sync to be resumed in order to upload them to the cloud....so if you don't resume syncing, they'll sit there on the local disk. However, doing that is rather silly as it means you have no backup for any of the edits that you do, and it also cuts you off from using LrMobile on your phones/tablets. It's just not a good idea in my opinion.