Moving photos from iCloud

All the pictures in iCloud are in your Mac Photos Library, if it's connected to iCloud. The best way to edit those pictures using Photoshop is to use Mac Photos!

In Mac Photos you can select the picture you want to edit and then, from the Menu bar, you can choose "Image>Edit with" -- and from the menu that pops up, you just choose Photoshop. You edit the picture, save it, and Photos records the save. This is great, because the pictures stay in the Photos system. The pictures edits sync with iCloud and all your devices. And, as with edits in Photos, the original picture remains unchanged, and you can "revert to original" later if you want.

Here is some more information:

Edit with third-party apps and extensions in Photos - Apple Support