While there isn’t a dedicated tags filter, there is a general filter you can use: wpdc_publish_body. In your case it’ll look like this
add_filter( 'wpdc_publish_body', function( $body, $remote_post_type, $post_id ) {
// code to get the post policy category
if ( // if there is a post policy ) {
$policy_tags = // map the post policy category to the appropriate tag(s)
$body['tags'] = $policy_tags
}
return $body;
}, 10, 3);