ACF: Display category name using taxonomy field

Assuming that 3 is a category ID…

$term = get_sub_field('category_selector'); 
if( $term ) {
  foreach($term as $t) {
    $t = get_category($t);
    echo $t->name;
  }
}

In other words, it looks like ACF is just storing the ID, not the whole object, so you need to use that ID to grab the category object before you have access to the name, slug, etc.