With Steam Extension, Cannnot build

Now I am developing a game for Steam.
It is my first time to build a game for Steam, so it might be stupid question.

I tried to use this extension.

But when add this extension to my project, I can’t build and run. with this error window.
image
Bundle Windows Application run fine.

I read this page, but I can’t get the answer.

What I have to do to resolve this problem?