How to create private galleries
Private galleries allow you to assign specific users to see a gallery while making them invisible to everyone else.
Check the users from the list you want to have access. You can select as many users as you want.
Before making a gallery private and accessible to specific users, the users must first have their own user account. You can always create a new user account for them if they have not yet signed up by going to your WordPress admin > Users > Add New.