Tizen Developers

I'm failing to install a trivial app to samsung kiosk. I've built a web app with latest tizen studio (for tizen 4), signed it with a new certificate, added package XML and zipped them. But when I try to install it to kiosk (from URL), I'm getting some error. It can download it, but not install. I have a feeling that it's something related to signing, but I don't know what's failing exactly. I don't have access to the kiosk personally (it's in another country). I know this kiosk can run apps, and I even have one that it's running now, and I've copied all settings from there already.