I can't sync photos from Icloud to win10 pc with icloud for windows

I can't cync photos from icloud to my pc after I had to reinstal win10 on my computer.

It all started with problems with my computer. I decid to reinstal win10. After that I had to reinstal a number of my programs. Mostly everything went well except "icloud for windows". When I try to use it I get a sign telling me:

Icloud picture could not be stored in D:\.....\Pictures\Icloud Photos\\photos and can not start.

Restart computer.

Why it can't store photos in that catalog I can't understand. I had my photos before reinstallation stored there.

What is it that can't start, sync of photos or something else?

Please could someone get me feed back of what the problem is to why it can,t store my photos on my computer.