iCloud photo download to pc

Hi everyone, I hope someone can help as at a loss to next steps. I would like to download my iCloud pics to my pc but when they download they go into a zip file. When I open the zip file I can’t access half the photos. I then sync’d my phone and iCloud pics as I then thought I could transfer from phone to pc (Via a cable) but although I can see all photos (including those on iCloud) it will only pick and transfer my iPhone photos. I have followed all online help but short of whatapping 1000 photos to myself i am at a loss as to how to make it work. Any suggestions appreciated. Thanks