NDK build fails

To develop native app

as explained here
I build the NDK.
But finally, I get the following failure error:

Summary: 1 task failed:

The folder is empty.

What should I do to make the build successful?

We do not guarantee the compatibility of webOS TV apps with webOS OSE resources. For webOS TV apps, please use webOS TV resources in this website only. And currently, webOS TV NDK is only available for contracted partners of LG. For questions about LG partnership, please contact your local LG office. If you don’t have the contact information, you can contact LG customer service center first. Thank you.

Where can I contact the local LG office?

Sorry for the confusion. Please visit https://seller.lgappstv.com > 1:1 Q&A > Partnership and discuss this with them. Thank you.