Fist check the every available options on Featured Section including custom slider as well. If you create custom slider, you can have options to add the button link on the every slider. Can you please check once the Featured Slider Selection and select the Custom slider and create your own slider using image, text, descriptions and Button text and link. I think, this is the requirement for you. Please play with the available options on the customizer, it will help to customize the theme easily.
Regards