3D FlipBook - Hi, i’m interested in your plugin after testing the demo, but i’m wondering : how do you use the “Lightbox activation

Hi, i’m interested in your plugin after testing the demo, but i’m wondering : how do you use the “Lightbox activation link” ? (the thumbnail is very small in the plugin so i would like to use an image from my wordpress media ) . i didn’t find any information in the guide about this feature. Thanks