Parsing JSON into Google spreadsheet (Apps Script)

This is the final version of the code. I hope this will help developers on JS and Apps Script when working with the Diadoc API.

Due to the fact that I have 3 organizations, I need to do an additional cycle:

for (let i = 0; i < boxId.length; i++) 

If necessary, this cycle can be removed.

function GetEmployees() {

  clearOrgSheets()

  var DdocAuthKey = GetAuthToken() 

  let options =
    {
      method: "GET",
      contentType: 'application/json',
      headers: {authorization: "DiadocAuth ddauth_api_client_id=" + DdocAPIkey + `,ddauth_token=` + DdocAuthKey}
    }

  for (let i = 0; i < boxId.length; i++) {

    let sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName(SheetNames[i])
    let pageNum = 1

    do {                             

      let url = `https://diadoc-api.kontur.ru/GetEmployees?boxId=`+ boxId[i] + `&page=` + pageNum + `&count=50`
      
      pageNum++        
                           

      var obj = JSON.parse(UrlFetchApp.fetch(url, options))

      var table = []; // it will be the 2d array

      for (var employee of obj.Employees) {

        var {LastName, FirstName, MiddleName} = employee.User.FullName;
        var name = [LastName, FirstName, MiddleName].join(' ').trim();

        var actions = {};
        employee.Permissions.Actions.forEach(a => actions[a.Name] = a.IsAllowed);

        var row = 
        [
          employee.User.UserId,
          name,
          employee.Position,
          employee.User.Login,
          employee.User.IsRegistered,
          employee.Permissions.IsAdministrator,
          actions.SignDocuments,          // Can sign documents
          actions.AddResolutions,         // Can coordinate documents
          actions.RequestResolutions,     // Can request document approval
          actions.CreateDocuments,        // Can create documents and work with drafts
          actions.DeleteRestoreDocuments, // Can delete documents and drafts, restore documents
          actions.ManageCounteragents,    // Can work with a list of counterparties
        ];

        table.push(row);
      }

      let lastRow = sheet.getLastRow() + 1

      try{
      let range = sheet.getRange(lastRow, 1, table.length, table[0].length )
      range.setValues(table);
      } catch (err){
        break
      }
    } while (obj.Employees.length > 0);
  }
}

Try this:

function myFunction() {

  // here is your object (parsed json)
  var obj = {
    "Employees": [
      {
        "User": {
          "UserId": "4d132227-ea5c-4e57-b105-2f8b97872545",
          "Login": "test@gmail.com",
          "FullName": {
            "LastName": "Фамилия",
            "FirstName": "Имя",
            "MiddleName": "Отчество"
          },
          "IsRegistered": true
        },
        "Permissions": {
          "UserDepartmentId": "b5072e57-1e96-490b-ae03-2fd52ef84a3a",
          "IsAdministrator": false,
          "DocumentAccessLevel": "SelectedDepartments",
          "SelectedDepartmentIds": [ "b5072e57", "cd2e04dc", "36e4434b" ],
          "Actions": [
            { "Name": "CreateDocuments",        "IsAllowed": true  },
            { "Name": "DeleteRestoreDocuments", "IsAllowed": true  },
            { "Name": "SignDocuments",          "IsAllowed": true  },
            { "Name": "AddResolutions",         "IsAllowed": true  },
            { "Name": "RequestResolutions",     "IsAllowed": true  },
            { "Name": "ManageCounteragents",    "IsAllowed": false }
          ],
          "AuthorizationPermission": { "IsBlocked": false }
        },
        "Position": "Специалист по снабжению",
        "CanBeInvitedForChat": true,
        "CreationTimestamp": { "Ticks": 637284074150000000 }
      }
    ],
    "TotalCount": 214
  };

  var table = []; // it will be the 2d array

  for (var employee of obj.Employees) {

    var {LastName, FirstName, MiddleName} = employee.User.FullName;
    var name = [LastName, FirstName, MiddleName].join(' ');

    var actions = {};
    employee.Permissions.Actions.forEach(a => actions[a.Name] = a.IsAllowed);

    var row = [
      employee.User.UserId,
      name,
      employee.Position,
      employee.User.Login,
      employee.User.IsRegistered,
      employee.Permissions.IsAdministrator,
      actions.SignDocuments,          // Can sign documents
      actions.AddResolutions,         // Can coordinate documents
      actions.RequestResolutions,     // Can request document approval
      actions.CreateDocuments,        // Can create documents and work with drafts
      actions.DeleteRestoreDocuments, // Can delete documents and drafts, restore documents
      actions.ManageCounteragents,    // Can work with a list of counterparties
    ];

    table.push(row); // add the row to the 2d array
  }

  // put the 2d array on the sheet  
  SpreadsheetApp.getActiveSheet()
    .getRange(2,1,table.length,table[0].length)
    .setValues(table);

}

Let me know if it works.