Added the assets
created appx folder in the build directory, keep the package.json as mentioned above.
3)Make sure the app logos named should be specific as metioned in the link .PNG format.
4)Earlier I had icon names as e.g: Square44x44Logo.png format .PNG then after changing the name to Square44x44Logo kept format .PNG as it is I was able to solve installed app issue.
What i realized by this is naming convention does matter a lot in case of applying icons. So the main issue caused due to pont 4.