Creates spreadsheet '_Index' with all the files and links to them in your google drive recursively.

index-files-from-folders.js

function myFunction() {
  var folderlisting = '_Index';
  
  var folder = DriveApp.getRootFolder();

  var ssfl = SpreadsheetApp.create(folderlisting);
  sheet = ssfl.getActiveSheet();
  
  sheet.appendRow(['Name','Url']);
  
  getFiles(sheet, folder, '');
};

function getFiles(sheet, folder, namePrefix) {
  var contents = folder.getFiles();
  
  var file;
  var name;
  var link;
  var row; 
  while(contents.hasNext()){
    file = contents.next();
    name = file.getName();
    link = file.getUrl();
    sheet.appendRow([namePrefix + '/' + name, link]);
  }
  
  var subfolders = folder.getFolders();

  while(subfolders.hasNext()) {
    var child = subfolders.next();
    getFiles(sheet, child, namePrefix + '/' + child.getName())
  }
};