Clean Portfolio | Free Theme | Featured Slider Image Issues

I'm trying to make the featured slider show images of my artwork. Every time I enable the featured slider it only shows the demo images (mountains, etc.). Is the ability to customize the images on the Featured Slider a Pro theme feature only? If not, how do I get my images to replace the demo images? Things I have done: 1. Dashboard > Featured Content > I created three featured content entries with featured images for each. I also put an image block with the same image as the featured image for each entry and published them. 2. Customizer > Theme Options > Featured Slider > "Homepage/Front page." 3. Customizer > Theme Options > Featured Content > I set "Featured Content 1, 2, 3" to specific Featured Content entries I already created.