[Plugin: WP Photo Album Plus] How to display Parent Albums thumbnails

I created some empty albums and created many sub-albums under those empty parent albums. But the display shows nothing but links to see sub-albums. Is there any way that we can make those empty albums show the thumbnails of their sub-albums? Or is there anyway that we can create categories instead of putting sub-albums into empty albums?

https://www.ads-software.com/extend/plugins/wp-photo-album-plus/