It is possible to set up a blog – template page where only the selected category would be displayed. And on another page there would be a blog with a different category? For example, https://www.ujfi.fei.stuba.sk/wordpress/?page_id=530 will display only article in category FYZIKA MATERIÁLOV
Try to use shortcode like this [latest-news showposts="3" cat="category"]. If it still not work please send your site URL and the login details to support@flythemes.net so we can check.