https://www.pbainbridge.co.uk/2019/01/student-feedback-system-bulk-add-drive.html

Bulk add Drive permissions.gs

function addPermissions() {
  
  // get relevant Sheets
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  
  var groupSheet = ss.getSheetByName('Groups');
  var groupSheetName = groupSheet.getSheetName();
  var groupSheetValues = groupSheet.getDataRange().getValues();
  var groupLastRow = groupSheet.getLastRow();
  
  var tutorSheet = ss.getSheetByName('Tutors');
  var tutorSheetValues = tutorSheet.getDataRange().getValues();
  var tutorLastRow = tutorSheet.getLastRow();
  
  ss.toast('Starting to add permissions to each Group');
  
  
  // loop through each Group *********************************************************************************
  for (var i=1;i<groupLastRow;i++) {
    
    // loop through Tutor 1 and Tutor 2 **********************************************************************
    var tutorDetails = [] // create empty array to push tutor details into
    for (var k=1;k<=2;k++) {
      var tutorName = groupSheetValues[i][k]; // get Tutor name
      Logger.log('Tutor name is: ' + tutorName);
      tutorDetails.push(tutorName); // add details to array
      
      // loop to get Tutor email address **********************************************************************
      for (var j=1;j<tutorLastRow;j++) {
        
        if (tutorName == tutorSheetValues[j][1]) {
          Logger.log(tutorName + ' matches ' + tutorSheetValues[j][1]);
          // if match found then get corresponding email address from column 1
          var tutorEmail = tutorSheetValues[j][0];
          Logger.log('Tutor email is ' + tutorEmail);
          tutorDetails.push(tutorEmail); // add details to array
          Logger.log(tutorDetails);
        }
        
      }// end of loop to get Tutor email address **************************************************************
      
    }// end of loop through Tutor 1 and Tutor 2 ***************************************************************
    
    // extract ID from file URL
    var groupFileURL = groupSheet.getRange(i+1, 4).getFormula();
    
    // check Group File Link is not blank before proceeding
    if (groupFileURL) {
      var groupFileID = groupFileURL.match(/[-\w]{25,}/); // regular expression to get continious string for ID
      Logger.log('Group File ID is ' + groupFileID);
      var groupFile = DriveApp.getFileById(groupFileID);
      
      // loop through Tutors adding them as editors ***********************************************************
      Logger.log(tutorDetails);
      for (var l=1;l<tutorDetails.length;l+=2) {
        var tutor = tutorDetails[l];
        groupFile.addEditor(tutor);
      }// end of loop through Tutors adding them as editors ***************************************************
      
      
      // open Group Sheet to add relevant Tutor details *******************************************************
      var sheet = SpreadsheetApp.openById(groupFileID);
      var newSheetGroup = sheet.getSheetByName('Group Feedback');
      var newSheetTutors = sheet.getSheetByName('Tutors');
      
      // add Tutor details into Tutors sheet from array
      newSheetTutors.getRange(2, 1).setValue(tutorDetails[1]);
      newSheetTutors.getRange(2, 2).setValue(tutorDetails[0]);
      newSheetTutors.getRange(3, 1).setValue(tutorDetails[3]);
      newSheetTutors.getRange(3, 2).setValue(tutorDetails[2]);
      
      // add Tutor details into Group Feedback sheet Headings from array
      // add Tutor details into Column headings
      newSheetGroup.getRange(1, 3).setValue('Tutor 1: ' + tutorDetails[0]);
      newSheetGroup.getRange(1, 7).setValue('Tutor 2: ' + tutorDetails[2]);
      // end loop of open Group Sheet to add relevant Tutor details *******************************************
      
      
      ss.toast('Tutors added to ' + groupSheetValues[i][0] + ' file');
      
    }
    else {
      ss.toast('Group File Link missing for ' + groupSheetValues[i][0]);
    }
    
  }// end of loop through each Group **************************************************************************
  
  
  ss.toast('Task completed');
  
} 


function onOpen() {
  SpreadsheetApp.getUi()
  .createMenu('Feedback')
  .addItem('Add Sheet Permissions', 'addPermissions')
  .addToUi();
}