function clear_spreadsheet() {
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var sheet = ss.getActiveSheet();
  sheet.clear();
  sheet.appendRow(['Name', 'Folder','Link', 'Last Updated']);
 }

function listFolders(folder) {
folder = folder || DriveApp.getRootFolder();
var ss = SpreadsheetApp.getActiveSpreadsheet();
var sheet = ss.getActiveSheet();

var file;
var name;
var urllink;
var row;
var currentfolder;
var lastupdated;
var files = folder.getFiles();

while ( files.hasNext() ) {
 file = files.next();
 name = file.getName();
 urllink = file.getUrl();
 currentfolder = file.getParents();
 lastupdated = file.getLastUpdated();
 sheet.appendRow( [name, folder, urllink, lastupdated]);
}

var subfolders = folder.getFolders();

while (subfolders.hasNext()) {
listFolders(subfolders.next());
}

};

function Run_Update(Folder) {
clear_spreadsheet();
listFolders();
}

var output = [];
while (files.hasNext() ) {
 file = files.next();
 name = file.getName();
 urllink = file.getUrl();
 currentfolder = file.getParents();
 lastupdated = file.getLastUpdated();
 output.push([name, folder, urllink, lastupdated]);
}
if (output.length) {
  var lastRow = sheet.getRange.getLastRow();
  sheet.getRange(lastRow + 1, 1, output.length, 4).setValues(output);
}