How can I get Slick Slider to display the images?
I accomplished what you're trying to do using Slick Carousel together with Slick Views.
You can create a content-type that you intend to be aggregated into the slideshow.  In my case a testimonial type consisting of a background image and overlying text.
You can create a views block and set its format to Slick Carousel.  You will be provided with setting options to configure the slideshow as you wish.
Filter your view by the content-type you want to comprise your slideshow, in my case testimonial.
lastly, pull your views block slideshow into another piece of content via entity reference.