extra-dev

masterClientFolder.addFolder(clientFolder);
DriveApp.getRootFolder().removeFolder(clientFolder);

extra-dev

var masterClientFolder = DriveApp.getFolderById("XXXXXX");

extra-dev

var clientFolder = DriveApp.createFolder('Alice');//insert client name here inside ' ' 

extra-dev

function createFolderStructure() {
  
  //Create the new folder
  var clientFolder = DriveApp.createFolder('Alice');//insert client name here inside ' ' VERY IMPORTANT FILL IN 
  
  //Get the master folder
  var masterClientFolder = DriveApp.getFolderById("XXXXXXXX");//ID for Current Clients folder goes here inside " "
  
  //add new folder to current client folder
  masterClientFolder.addFolder(clientFolder);