i have problem to get the document's id that automatically created and its specific value from in firestore database. here the firestore database that i have also the code that i tried to: firestoredb

app.post("/Register", (req, res) => {
  const {
    name,
    email,
    password,
    phone,
  } = req.body;
  const balance = 0;
  const lowEmail = email.toLowerCase();
  const valAcc = db.collection("Users");
  const valueEmail = valAcc.getString(lowEmail);
  if (valueEmail === lowEmail) {
    res.status(400).send("Email already exists");
  }
  db.collection("Users").add({
    Name: name,
    Email: lowEmail,
    Password: password,
    Phone: phone,
    Balance: balance,
  });
  res.status(201).send();
});

And i am using it for making api with node.js. any solution for this? i tried to search for it but i didnt get it. Any help will be very valuable. Thank you.