IF it's still not working for you, I had forgotten to add the fa-ul
class onto the parent (UL) element:
<ul class="fa-ul">
Together with the 2 bits of advice provided already by others:
a) font-family: 'Font Awesome\ 5 Free';
b) font-weight: 900;
solved it for me.
FWIW, the include in my <head>
tags is just:
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.14.0/css/all.min.css" integrity="sha512-1PKOgIY59xJ8Co8+NE6FZ+LOAZKjy+KY8iq0G4B3CyeY6wYHN3yt9PW0XpSriVlkMXe40PTKnXrLnZ9+fkDaog==" crossorigin="anonymous" />
And I am using this with React and Preact. No need for any special React npm installs or components.