Thank you so much for using our theme Quality Construction.
This is the free theme and we haven’t tested the visual composer plugin. We are developing the premium theme and it will be available within a week and in the pro version, you will have Page builder plugin compatible.
You can use the available widget, widget area to make the site as our demo easily. In addition, you can check the video for making the site as demo with the help of docs as well.
Let us know if you need any more details information.