If you are using the latest version of the plugin, you need to change your syntax to the following: $name = $_POST['acf']['field_57c072a1a59c4'];
You may also want to hook into the acf/save_post filter instead of the acf/pre_save_post.
You can also change the slug by making use of the ‘post_name’ argument when generating the $post data.
I hope this info helps.
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