To on the front page was a slider of sticky posts, you need to:
1. As a front page to assign a static page.
2. For a static page assigned as the front display, you need to assign the Front Page template (Page Attributes box: Template, on page editing screen).
3. Assign Sticky* at least 2 posts with uploaded the Featured Image.
* How to Make Sticky Posts?
When you create a new post or edit, look towards the right hand sidebar where you will see a Publish box. Look at the (Visibility: Public) field and click edit. Check the box to make the post Sticky. Press Publish/Save.
4. Check Slider Sticky in the Customizer Front Page Options.