Thank you so much purchasing our theme and contacting our support center.
Could you please send us your admin access because currently, we don’t see your website because of maintenance mode enabled? We suggest you also watch our installation video tutorial how to set up the theme and import all data. https://www.youtube.com/watch?v=0QPBt-lRWLA
We don’t know why, but the slider was not imported with Dummy Content. But you can do this easily via admin panel -> Slider Revolution -> Import slider. You can find all import files in the theme folder basel/inc/dummy-content