Insert posting automatically based in acf field

Before inserting check if post exists:

$exists = get_page_by_title( get_field('fornecedor'), OBJECT, 'fornecedores');

if ( empty( $exists ) ) {
  wp_insert_post( array(
    'post_status' => 'publish',
    'post_type' => 'fornecedores', // post_type which is created posting
    'post_title' => get_field('fornecedor'), // Custom field to generate the post type
    'post_content' => ''
  )
}