Migrating photos from Lightroom Mobile to Classic

I need some help getting some photos out of the cloud and into the folder hierarchy on my desktop. Sounds like a straightforward migration from Lightroom Mobile to Classic, but I think I've complicated things a bit. To explain:

I was a long-time user of Lightroom Classic on my laptop, so I had a few thousand photos stored locally on my laptop's hard drive. Then my laptop started to die, so I downloaded Lightroom, signed up for an account, and uploaded all my original photos to the cloud. The next day, my laptop finally completely died.

Next, I purchased an iPad Pro to replace my laptop. When the iPad arrived, I downloaded Lightroom Mobile, signed into my Adobe account, and happily continued adding photos and editing them there. No problems yet.

I have since upgraded again to an iMac running Lighroom Classic, and I'd like to download all my original photos from the cloud. The photos I have taken since upgrading appear on iMac's SSD in the Navigator panel. These have been synced with Lightroom Mobile via a Collection. But all the originals I uploaded to the cloud do not--all I see are previews.

How should I go about downloading the original photos from the cloud so that they are stored locally on my iMac's SSD? Also, how should I go about deleting the originals from the cloud and replacing them with previews so I can continue editing them on my mobile devices?

Thanks! Your help is greatly appreciated!