get_author_posts_url() Not working

get_the_author_meta()

get_author_posts_url()

get_avatar_url()

You are using all three of these functions incorrectly. Please always check the documentation first. get_the_author_meta() does not require any arguments, but you can supply the field you wish to be returned. get_author_posts_url() requires the user_id. get_author_posts_url() and this one is a bit more flexible and will take a user_id or various Objects.

The code sample below should work…

$author_id = get_the_author_meta( 'ID' );
$author_link    = get_author_posts_url( $author_id );
$author_avatar  = get_avatar_url( $author_id );
$featured_image = wp_get_attachment_image_src( get_post_thumbnail_id( $post->ID ), 'full' );

echo '<div>
        <div class="">
            By <a href="' . esc_url( $author_link ) . '">Author</a>
        </div>
    </div>';