How to provide an option to save a post as a draft

To let the user choose whether a form-created post is published immediately or saved as a draft, add a field with explicit options for the post status, then read it in af/form/editing/post_data to set post_status accordingly.

For the example below: add an ACF radio field named publish_when with two choices — now and later.

add_filter( 'af/form/editing/post_data', function ( $post_data, $form, $args ) {

    // Only run for the target form.
    if ( $form['key'] !== 'YOUR_FORM_KEY_HERE' ) {
        return $post_data;
    }

    $when = af_get_field( 'publish_when' ) ?: 'now';

    $post_data['post_status'] = $when === 'later' ? 'draft' : 'publish';

    return $post_data;

}, 10, 3 );

You can extend the same pattern to support more statuses (pending, private, scheduled future) — just map the field options to the post status values you want.