Can I share an item with people who aren't signed in?
đź”´ StageStock
You can't. Anyone viewing an item has to be signed in to your StageStock site, whatever the item's visibility is set to.
Shared Publicly is a choice in an item's Visibility field, but today it behaves exactly like Internal: every signed-in user assigned to the item's category can see it, and nobody else. Shared Privately works the same way. Only Restricted changes who sees an item, limiting it to people with permission to view restricted items.
The option is there so you can mark items as you create them. A page that anyone can open without signing in is a feature request, and you can read about it or add your voice here.
All four options, explained: Item visibility settings