iCloud photo library

. If I go to general, summarize photos and copy items to photo library is checked,

That is good - copy items should be checked, summarize it not important in this case.

under iCloud , download originals to this Mac is checked but it's gray - I can't undo it. Nothing else is checked

It should be checked, but I have never seen it grayed out. That is unusual.

If I check on iCloud Photo Library it tells me I need to buy more storage .... Hope I'm making sense.

What does the System Preferences > iCloud panel show at the bottom?

There should be a bar showing how much iCloud storage you have used.

That is why I want to see for myself.

Your Photo Library is switched off (no checkmark) so I have no idea where your photographs are now. When you answered yes o my question regarding photos and where they were what made you say that they were in the photo library?

Also please browse to https://www.icloud.com/#photos

And tell me what you find there (it should be your photos),

Try to download all photos you can save right now from the iCloud webpage:

Open the Photos.app at
https://www.icloud.com,

While viewing the photos click "Select Photos", select the photos, then click the download button.

That is why I want to see for myself.

Good point!

Conflicting results, one picture shows the library as being switched off yet you say there are photos in it.

Follow Leonie's directions to download the 3500 that are there.

What are you doing?