Photo back up to iCloud

When it has finished syncing your photos on iCloud should be organized in the same way as they are on your Mac (they are on mine). Note that the syncing process can take quite awhile (days). Also, it has been several years since I first synced my much smaller photo library and when I did it, the album/folder organization appeared to be the last thing to sync.

Also, I always cringe just slightly when I hear the term backup used for iCloud Photos. I've never had a problem with iCloud Photos but I really value my photos so I insure that I have a local copy on my Mac (by not turning on the Optimize Photos option in the Photos app on the Mac) and I also make a backup to an external USB drive. Syncing with iCloud Photos has some of the benefits of a backup (and the benefit of being offsite) but is not the same as a backup. A major difference is the fact that if you delete something, accidentally or otherwise, there is only a limited time period (30 days in most cases) during which it can be recovered.

As FoxFrith says - iCloud is not backup. Just buy a new external hard drive (it doesn't need to be a time capsule) and set up time machine to backup to that drive.

The problem with iCloud for photos (and files if you use iCloud drive) is it makes all the libraries across all the devices the same. While it does protect you from a drive failure - it doesn't protect you from accidental deletion. If you delete photos on your phone, they are deleted on your mac, and from iCloud - same if you delete on your mac - they'll be deleted on your phone. There have been rare cases of system failure also causing deletions (or just user error). There are also numerous examples of library corruption making it very difficult to access photos.

Every few days we get someone here saying "I deleted photos - how can I get them back". If it was more than 30 days ago, and there is no other backup, the answer is "you can't"