1- Make sure you have Node.js installed.
2- If you're using VSCode, make sure to download: Live Server Extension and Live Sass Compiler.
3- Open the directory in your terminal and run:
$ npm install
4- To build and watch for changes run:
$ npm run build
5- To make sure everything works, click on "Watch Sass" and "Go Live" in the bottom right if you're on VSCode (do the equivalent if you're not).
Then, go to ./index.html and try removing one of the Tailwind classes <... class="underline" ...>. If the website changes it means TailwindCSS works.
Next, go to ./Project/Styling/index.scss and make some changes, if the site changes that means SCSS works. Remember to ALWAYS run npm run build everytime you want to change anything in the ./Project/Styling/ folder.