I don't own an iphone, so can't test out any potential solutions for you.
But I'm confident that if you were not logged-in, your photos will have been downloaded from your cell phone into your computer (only). No way will those photos be currently stored in your cloud storage account, because you weren't logged-in
to it at that time.
The only sure way to transfer the photos now is to connect your computer to an external storage device (e.g. a USB thumbdrive), and copy the photos to it.
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