Hi hugooc,
Thanks for reaching out to Apple Support Communities.
It sounds like you're having an issue with turning on iCloud Photos.
We're happy to assist.
We recommend checking out the steps in the section titled "Turn on iCloud Photos" from the article here: Set up and use iCloud Photos - Apple Support
Make sure that you set up iCloud and sign in to iCloud with the same Apple ID on all of your devices. If you have a PC, you need Windows 7 or later and iCloud for Windows.
On your iPhone, iPad, or iPod touch
1) Go to Settings > [your name].
2) Tap iCloud.
3) Tap Photos, then turn on iCloud Photos.
On your Mac
1) Choose Apple menu > System Settings or choose Apple menu > System Preferences.
2) Click Apple ID.
3) Click iCloud in the sidebar, then select Photos.
On Apple TV 4K and Apple TV HD
1) Go to Settings > Users and Accounts.
2) Select iCloud.
3) Turn on iCloud Photos.
The reason why we're recommending the steps above is because they directly address the issue you initially posted about: you're unable to turn on iCloud Photos.
Should the issue continue, try booting your computer in safe mode, followed by testing to see if you can turn on iCloud Photos there.
Start up your Mac in safe mode - Apple Support
If you're not having any luck with turning on iCloud Photos when in safe mode, try creating a new user on your Mac and let us know if you can turn on iCloud Photos there.
Change Users & Groups settings on Mac - Apple Support
Please do not hesitate to reach back out to us if you have more questions.
Cheers!