Download iCloud photo to windows pc.

Go to iCloud.com. Don't sign in. Above the prompt to sign in you'll see a banner that says 'iCloud for Windows'. Click the download link. Once this app is downloaded, sign in with your Apple ID> click 'options' to the right of photos. You can select to download photos from iCloud on this 'window'> click 'apply'. By downloading this app, all of your photos in iCloud will automatically download to your PC. Effortlessly!

Use the internet browser on the PC, log into iCloud.com, go to the Photos app there, select the photo(s), click the download icon in the bar at the top.