photo library sharing

• To be using iCloud Shared Library you have to subscribe to an iCloud storage plan and pay for the storage used for the shared photos. You can only share photos from an iCloud Photos Library, so you need enough cloud storage to keep your complete photos library in iCloud, plus the shared photos by others. And you need to be patient - it takes several days for the shared library to be set up, if your library is large. Your shared library will be shared as a flat list of photos and videos, only the media files in the full resolution and with all metadata, but the structure of the library (albums and folders) will not be shared.

• Shared Albums on the other hand are free and do not count against any of your paid cloud storage. The photos and videos will be shared at a reduced resolution, optimized for sharing, and many metadata will be stripped for privacy reasons. But you can share albums this way. Set up Shared Albums in iCloud on all your devices – Apple Support (UK)

Have you been trying to share shared albums or a shared iCloud Photos Library? Do you want to share the photos at the full resolution with locations, titles, and other metadata, or do photos optimized for sharing with the metadata stripped suffice? Are you willing to pay for the shared storage?

Shared libraries and shared folders are two very different things that do not overlap. Which are you trying to use?

As far as I know, neither has any distance limitations.