Can not edit front page with visual builder at Emmet theme?

The front page layout of Emmet theme is one of the main features of this theme. You can edit Home Page via your WordPress dashboard>Appearance>Customize. There is used page template called 'Customizable Front Page' and it is built with custom section and widget areas.

If you want to build your Home Page using Content Editor plugin you need to switch page template of Home Page to 'Full Width' or 'Landing Page'. Then you will be able to use Page Builder plugin to build the Front Page.