[iMore Question]

I cannot for the life of me find out how to do this and I don't know what I'm doing wrong. I've been trying for an hour and a half now and still have absolutely nothing.

[lantzaut]

You can download iCloud app on computer and download photos from iCloud afterwards.

[gnirkatto]

Without having all details about your IT environment, I assume that your pictures were stored in iCloud Drive. You have to get them into the photos app to make them synch over to the iPhone.
If you have a Mac, you can open iCloud Drive in Finder, and easily drag & drop pictures over to the photos app.
On the ipHone, you can open the relatively new files app, mark pictures there, and "share" them over to the photos app. Of course you can also open & view pictures right within the files app, but less conveniently than in the photos app.
Maybe there are easier ways that some Apple gurus who know more than I do know of.....