Downloading Photos From iCloud Errors

I have about 22000 photos and videos on iCloud. I'm would to download them to a back up disc.

If I try to download them from iCloud on the web I can download them singly. If I select two photos ICloud goes to a blank screen with the word "Not Found". If I bulk select photos and try to download them it says "Items cannot be downloaded due to a server error."

Not to be deterred I went onto the "Security and Privacy" service and asked for my photos to be sent to me. I only received videos, but no photos.

I can still see the photos one at a time on my computer but I want to create a disc back-up so I can make sure my family have access to them.