I bought more space on iCloud for my pictures, but they won't transfer to iCloud.

See -> Access and view iCloud Photos on your iPhone, iPad or iPod touch

Access and view iCloud Photos on your iPhone, iPad or iPod touch – Apple Support (UK)

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Do more with your photos

• Transfer photos and videos from your iPhone, iPad or iPod touch.
• Download photos and videos from iCloud.
• Take and manage photos.
• Set up and use iCloud Photos.
• Reduce the size of your iCloud Photos.
• Get help with iCloud Photos.
• Check your iCloud storage.

I'm sorry, but this answer is completely not helpful. I have this problem too. I have purchased all the way up to a 2TB iCloud plan trying to free up space on my mac because I have a decent amount of pictures. No matter what I do, I can't get the pictures to move up to the iCloud. If I try to copy them up there, i get the you don't have enough space message even though I have only used about 1% of the 2TB plan. Then if I try to keep importing pictures that I need to import from my camera, I get the problem of not having enough space on my mac still. I've only got about 500MB left on my Mac but no matter what I do, I can't free it up. Help!!!!!! Just resending those links above to everyone who asks this question is not helpful!