I continued to play around and thought maybe the slides couldn’t have URLs associated with them in order for the lightbox to work. I removed the URLs (to full-size versions of the slider images) and my slides now open in a lightbox. I didn’t realize the URL box had to be left empty in order for the lightbox feature to work. I use Fancybox all the time to open full-size images in my non-WordPress sites. Such behavior would be a great addition to Meta Slider.
I’m sorry for my lack of understanding in getting this plugin up and running.