I am using Sass and in the Fontastic page add 6 icons to be embedded in the page but they do not appear.
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
<link href="https://file.myfontastic.com/H3XXN7wMjz3R3tuYbzimaZ/icons.css" rel="stylesheet">
<link rel="stylesheet" href="css/styles.css">
</head>
<body>
<!--Header-->
<header class="main-header main-container">
<div class="main-header-1">
<img class="logo" src="https://ed.team/themes/custom/escueladigital/img/EDteam-logo.svg?12-oct" >
</div>
<div class="main-header-2">
<!--Widget de contacto-->
<div class="contact-widget">
<!--Icono-->
<div class="contact-widget__icon icon-call button button--dark button--square"></div>
<!--Datos-->
<div class="contact-widget__data">
<h3 class="contact-widget__title">Call now</h3>
<p class="contact-widget__content">987-654-321</p>
</div>
</div>
<!--Widget de contacto-->
<div class="contact-widget">
<!--Icono-->
<div class="contact-widget__icon icon-location button button--dark button--square"></div>
<!--Datos-->
<div class="contact-widget__data">
<h3 class="contact-widget__title">Our location</h3>
<p class="contact-widget__content">Calle Los Manzanos 321 - Guadalajara</p>
</div>
</div>
<a href="#" class="donate button button--dark">Donate now</a>
</div>
</header>
<!--Menu Container-->
<nav class="main-nav">
<!--Menu-->
<ul class="main-menu">
<li class="main-menu__item"><a href="#" class="main-menu__link">Home</a></li>
<li class="main-menu__item"><a href="#" class="main-menu__link">About us</a></li>
<li class="main-menu__item"><a href="#" class="main-menu__link">Events</a></li>
<li class="main-menu__item"><a href="#" class="main-menu__link">Gallery</a></li>
<li class="main-menu__item"><a href="#" class="main-menu__link">Contact</a></li>
</ul>
<!--Redes sociales-->
<div class="social-network">
<a class="icon-facebook" href="https://facebook.com"></a>
<a class="icon-twitter" href="https://twiter.com"></a>
<a class="icon-youtube" href="https://youtube.com"></a>
<a class="icon-linkedin" href="https://linkedin.com"></a>
</div>
</nav>