Automatically group pictures in a post to a lightbox group

I would like to automatically group all images in a post for usage in LightBox.
I have followed the instructions on https://www.bloggerskills.com/lightbox-and-wordpress-the-easy-way/ and now my images are opening automatically in a lightbox pop-up. However when there are multiple images in a post I need to open/close everytime and it does not allow me to scroll through the images using Lightbox.

Any ideas?