child themes

How does the parent theme call these individual CSS files?

god I haven’t a clue. where do i look to find that information?

Site url?

https://www.unicorndesign.net/wordpress

The only thing I can see is an import line in style.css:
@import "css/screen.css";

But as this is a commercial theme whose template files are not freely available, you really need to seek support from the theme’s vendors.
https://themeforest.net/forums/topic/themeforest/themeforest