you made this right, the ID is the one in the url (when you edit the page / post / …). Have you checked the shortcode for the problem with the >> ” << signs?
I used your /smooth-slider page from the demo content and it worked perfectly but like I said it just disappeared yesterday after renaming the page to /home. How do I set it that it shows again?
When you edit a page or post, below the editor is a box with settings, there you can choose the “Slideshow” tab, choose the slider type and the source for the slider, then save the post / page. You can find this also in the theme documentation.