Modular Manufacturer licenses are issued by the SC Building Code Council.
Modular homes can be installed by a Residential Builder or General Contractor. Here is information on obtaining those licenses.
General Contractor License Application
Residential Builder License Application
A Certificate of Authorization (COA) allows a Residential Builder to operate an additional location
Certificate of Authorization Application
In many cases a real estate license is required to sell homes with land.
Real Estate Salesperson and Broker Licensing Requirements