Downloading thousands of photos from iCloud to external hard drive

Hi there! I have nearly 50,000 photos that I am trying to download from iCloud onto my external hard drive, via my Windows PC. Could you please help me find the quickest and easiest way to do this? My photos are of large file size due to the high quality of them. Currently I seem to be only able to download up to 1000 photos at a time and it is taking a very long time to do each batch. Is there a better way to do this? Thank you for your help!