Your first error is that when updating post meta using wp_update_post() your meta values need to be in a nested array, example: (see https://developer.wordpress.org/reference/functions/wp_insert_post/)
// Update current post with new preview link
$postInfo = array(
'meta_input' => array(
'field_5cf1142a132e8' => $url
),
'ID' => $postID
);
your second issue is that when updating fields in this manner you’d need to update 2 fields. One using the field name that holds the value and the second is the field key reference. The meta_key of this other field is "_{$field_name}" and the value of this field is the field key of the field you are updating.
