Author, Date, etc

First, create a child theme:
https://codex.www.ads-software.com/Child_Themes#How_to_Create_a_Child_Theme
Copy content-postlist.php to your child theme folder and open it in your text editor.

Find the line where it says

<h2><?php the_title(); ?></h2>

and add

<span><?php echo get_the_author(); ?></span>

after this line. Format as you wish.