Have a password-only landing page
Many Sunshine users password protect every single gallery. Some of you don’t want your users to see other galleries. You can create a simple password field landing page where users are prompted to enter their gallery password. If they enter a valid gallery password, they are then automatically taken directly to the gallery.
In your WordPress admin go to Pages > Add New, call it whatever you want.
For the content area, use the [sunshine-gallery-password] shortcode.