1. Make a copy of your index.php file
2. Rename file to category.php
3. Copy category.php to your child theme
4. Edit category.php in your child them and add the following code right after the tag: <div id=”left-area”>

<!-- add page title code start here -->
	<?php if ( have_posts() ) : ?>
		<header class="blog-title">
		<h1><?php printf( __( '%s', 'Divi' ), '<span>' . single_cat_title() . '</span>' ); ?></span></h1>
		<?php the_archive_description( '<div class="taxonomy-description">', '</div>' );?>
		<hr class="archive-line"/>
		</header>
	<?php endif; ?>	
<!-- add page title code start here -->

FYI: I modified the code and put a <h1> tag instead of <h2> because my crawler said these pages were missing <h1> tags.
Reference: https://quiroz.co/add-category-title-description-category-archive-pages/