Create a password protected gallery
When adding/editing a gallery, find the “Visibility” option in the Publish box in the right column. Click “edit”
Change the visibility to “Password Protected”. Enter a password. Optionally enter a password hint to help your clients remember the password.
Password protected galleries allow you to make a gallery only visible to people who first enter a password. A great way to allow a gallery to be visible only to your client or whomever else they want to share the password with.