Maybe this is not the right way to use fontawesome but it works: embed links to the fontawesome stylesheet in your site header and that's it!
Pick up an icon of your choice from the official website and place it wherever you want.
Code:<link rel="stylesheet" href="https://site-assets.fontawesome.com/releases/v6.4.2/css/all.css"> <link rel="stylesheet" href="https://site-assets.fontawesome.com/releases/v6.4.2/css/sharp-solid.css"> <link rel="stylesheet" href="https://site-assets.fontawesome.com/releases/v6.4.2/css/sharp-regular.css"> <link rel="stylesheet" href="https://site-assets.fontawesome.com/releases/v6.4.2/css/sharp-light.css">
This is how you need to do it. https://fontawesome.com/docs/web/setup/host-yourself/webfonts
Kits and other ways won't last long. it's best to use the self hosted way.