If you use the child theme you need to create dynamic.css file via FTP > http://prntscr.com/iowdld
If you do not use the child theme, you can download it here https://www.8theme.com/download-plugins/ and upload it to /wp-content/themes/ folder of your server (WordPress child theme is a theme that inherits the functionality of the parent theme. With child theme you can make modification or add additional functionality to parent theme. A child theme is the safest and easiest way to modify an existing theme, whether you want to make a few tiny changes or extensive changes.)
