WP-SCSS Sass Compiling Error: File Permission Error, permission denied. Please make the cache directory writable.

First, please update WP-SCSS plugin up to the latest version, then click WP Dashboard => Settings => WP- SCSS and re-save changes like on the screenshot: http://prntscr.com/107glfk

Alternative solution: please download the stable version of the WP-SCSS plugin here: https://drive.google.com/file/d/1WXuLwtf226TW5MgG9eWKTOn1I8YkFcvs/view?usp=sharing

Install it, but don't update to the latest version, because it is unstable.

Then if you want to change colors on your website, first of all, please click WP Dashboard => Plugins => All Plugins. Be sure that the WP-SCSS plugin is active. Then please create the folder with name "cache" in the plugin's directory: \wp-content\plugins\wp-scss

Then click WP Dashboard => Settings => WP-SCSS and apply the following options like on this screenshot: https://prnt.sc/ujc9ab

Input in SCSS location this path: /scss/

Input in CSS Location: /css/

Then save changes.  

Go WP Dashboard => Appearance => Customize => Theme Color Scheme:  https://prnt.sc/ujc9s4

Here you may change the default theme's colors to your corporate. Change colors and click the "Publish" button.

Wait some time and check the result at the front-end.