If your post bylines do not display an author name, you might have user and/or guest pages disabled.
Go to Molongui > Authorship Settings > Author Pages and make sure both Enable Guest Archives and Enable User Archives settings are enabled.
This happen because your theme uses the
get_the_author_posts_link WP core function to retrieve that information. If you want your bylines to display the author names keeping author pages disabled, please open a support ticket with us here.