Where has the "Additional CSS" gone?

According to this page: https://catchthemes.com/theme-instructions/catch-responsive/, "You can add your custom CSS that will overwrite the theme CSS for further design customization through “Appearance => Customize => Additional CSS”, in your WordPress Dashboard." But I can't find it no more. I had it in the free version, and I upgraded from free to pro, and it is gone. I need this!