Trying to join two collections together, array in collection map to other collection. MongoDB

In MongoDB with two collection, trying to get a course with the “courseCode”.
In the course collection “assignedTutors” is a array of users._id in the course collection.
Want to want the array of “assignedTutors” IDs to get their user info in the users collection.

Problem: With the current code I am not getting the user data in the users collection using the array of “assignedTutors” IDs. In the current example there are 3 user IDs in the “assignedTutors” array I would like to use aggregate to get the user data from the users collection.

If there is better way to do this i am open to that too.

course collection:

{
    "_id": {
        "$oid": "66e765c04ce5539d7f7362c2"
    },
    "courseCode": "ACB123",
    "courseName": "ABC",
    "courseImgUrl": "https://ABC.png",
    "coursePrice": "123",
    "assignedTutors": ["66f9a09505e0ca3203870633", "66f9a07e05e0ca3203870630", "66f9a05005e0ca320387062d"],
    "description": "This course ABC",
    "published": true,
    "school": "ABC school"
}

users collection:

{
    "_id": {
        "$oid": "66f9a09505e0ca3203870633"
    },
    "userName": "tutor3",
    "password": "xxx",
    "email": "[email protected]",
    "userType": "tutor",
    "firstName": "Tutor",
    "lastName": "Three",
    "teachingCourse": ["66f9adbb05e0ca3203870732", "66e765c04ce5539d7f7362c2"],
    "certificates": [],
    "purchasedCourse": [],
    "__v": {
        "$numberInt": "0"
    }
}

current code:

    module.exports.getCourseByCode = function (courseCode) {
        return new Promise((resolve, reject) => {
          Course.aggregate([
            {
              $match: { courseCode: courseCode }
            },
            {
              $lookup: {
                from: 'users',
                localField: 'assignedTutors',
                foreignField: '_id',
                as: 'assignedTutors'
              }
            },
            {
              $unwind: '$assignedTutors'
            },
            {
              $lookup: {
                from: 'users',
                localField: 'assignedTutors._id',
                foreignField: '_id',
                as: 'assignedTutors.tutorData'
              }
            },
            {
              $project: {
                _id: 1,
                courseCode: 1,
                courseName: 1,
                courseImgUrl: 1,
                coursePrice: 1,
                school: 1,
                description: 1,
                published: 1,
                assignedTutors: { $arrayElemAt: ['$assignedTutors', 0] }
              }
            }
          ])
            .then((courses) => {
                console.log(courses)
              if (courses.length === 0) {
                reject(`Course with code ${courseCode} not found.`);
              } else {
                resolve(courses[0]);
              }
            })
            .catch((err) => {
              reject(`Error while retrieving course with code ${courseCode}: ${err.message}`);
            });
        });
      };

Current output:

{
    "_id": {
        "$oid": "66e765c04ce5539d7f7362c2"
    },
    "courseCode": "ABC123",
    "courseName": "Test",
    "courseImgUrl": "abc.png",
    "coursePrice": "123",
    "assignedTutors": ["66f9a09505e0ca3203870633", "66f9a07e05e0ca3203870630", "66f9a05005e0ca320387062d"],
"description": "XYZ.",
"published": true,
"school": "ABC school"
}

I want it to return a course and with the assignedTutors data on the users collection.

{
    "_id": {
        "$oid": "66e765c04ce5539d7f7362c2"
    },
    "courseCode": "ABC123",
    "courseName": "Test",
    "courseImgUrl": "abc.png",
    "coursePrice": "123",
    "assignedTutors": [{
            "_id": {
                "$oid": "66f99b8005e0ca32038705f6"
            },
            "userName": "user1",
            "password": "zzz",
            "email": "[email protected]",
            "userType": "xxx",
            "firstName": "userF",
            "lastName": "userL",
            "teachingCourse": [],
            "certificates": [],
            "purchasedCourse": [],
            "__v": {
                "$numberInt": "0"
            }
        } {
            "_id": {
                "$oid": "66f99b8005e0ca32038705f6"
            },
            "userName": "user2",
            "password": "zzz",
            "email": "[email protected]",
            "userType": "xxx",
            "firstName": "userF",
            "lastName": "userL",
            "teachingCourse": [],
            "certificates": [],
            "purchasedCourse": [],
            "__v": {
                "$numberInt": "0"
            }
        }, {
            "_id": {
                "$oid": "66f99b8005e0ca32038705f6"
            },
            "userName": "user3",
            "password": "zzz",
            "email": "[email protected]",
            "userType": "xxx",
            "firstName": "userF",
            "lastName": "userL",
            "teachingCourse": [],
            "certificates": [],
            "purchasedCourse": [],
            "__v": {
                "$numberInt": "0"
            }
        }
    }],
"description": "XYZ.",
"published": true,
"school": "ABC school"
}