how do I download photos from iCloud to my computor

Sign in with Apple ID and password from a web browser at www.icloud.com with account credentials , in photos section

If photos are in series , hold the shift key click on rest of photos to get selected ( prefer to select small number of photos ) , also command and A keys work in Mac OS catalina 10.15.7 and click on download button see the article https://support.apple.com/guide/icloud/upload-and-download-photos-mmb5dbaf376f/icloud

Use the adapter, also known as the magical wire that charges your phone and plug it into the usb outlet on a computer , you will most likely have to unlock your iPhone and something should pop up on your computer. hope this helps!