The OP's issue was resolved going to DropBox and that's good.
But for anyone else contemplating using iCloud Files app to store lots of pictures — my advice is don't.
The Files App (iCloud) is probably the worst photo organizing/moving/storing/viewing solution available on the internet.
Everything about it seems geared towards making your life miserable when dealing with large quantities of photos. There's no selecting multiple items at once nor moving multiple items at once. Every action must be done one at a time. After a while it gets excruciating. Even the most basic web hosting service is superior to using the iCloud Files App for image collections.