How to extract the URL parameter value of a Google Spreadsheet using AppScript

I am working on some task automation from a Google Spreadsheet. I need to use Adobe Sign API to complete the process. I just started using AppScript last week, so I'm not sure if what I'm doing is right...

From the spreadsheet, I trigger a function that will open the oAuth request link of Adobe Sign to a new tab. User will sign in and click Allow Access. The redirect_uri I have setup is to the same spreadsheet so if the request is successful, it will redirect to the spreadsheet and the authorization code is included in the URL by Adobe Sign. (e.g. https://docs.google.com/spreadsheets/d/[spreadsheetId]/edit?code=[authorizationCode])

How do I get value for code parameter in the URL?

Adobe API reference for making an oAuth request - https://opensource.adobe.com/acrobat-sign/developer_guide/gstarted.html#create-an-authorization-request-link

I tried using e.parameter on onOpen event like below but its resulting into an error

TypeError: Cannot read properties of undefined (reading 'code') at onOpen

    function onOpen(e) {
      const code = e.parameter["code"];
      console.log(code);
    }

I have also tried implementing doGet(e), but not sure if I was doing it correctly. I'm getting error

TypeError: Cannot read properties of undefined (reading 'parameter')

I added a menu to trigger the doGet function:

function onOpen(e) {
  var ui = SpreadsheetApp.getUi();
  ui.createMenu('Document control')
 .addItem('Do Get', 'doGet')
 .addToUi();
  const code = e.parameter["code"];
  console.log(code);
}

function doGet(e){
  var code = e.parameter.code
  console.log(code);
}