Downloaded it just to test it for you and, it's even worse then I remember. I set the cam as generic> onvif and able to retrieve the image, but it's not loading in the main view. Anyway, I seriously recommend you to dump this app for tiny cam, or at least try it. The full version was $2 on black Friday, but you can try free one. In tiny cam you can use Hikvision profile but it will not give you ptz controls, use onvif instead.
Alternatively you can use Hikvision native app which is free and works well with Huisun.