How can I get the correct DatabaseReference

I am creating a user profile but I do not know how can I get the child node and display it in the user profile, How can I reference this correctly? I would greatly appreciate any comments or suggestion, thank you in advance!!

USER PROFILE

private void showUserProfile( FirebaseUser firebaseUser) {

String userID = firebaseUser.getUid();

DatabaseReference referenceProfile = FirebaseDatabase.getInstance().getReference("Users"); 
// 👆
referenceProfile.child(userID).addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(@NonNull DataSnapshot snapshot) {
        ReadWriteUserDetails readUserDetail = snapshot.getValue(ReadWriteUserDetails.class);
        if(readUserDetail != null){
            fullname = firebaseUser.getDisplayName();
            email = firebaseUser.getEmail();
            doB = readUserDetail.birthday;
            discount = readUserDetail.discount;

            textViewFullName.setText(fullname);
            textViewEmail.setText(email);
            textViewDoB.setText(doB);
            textViewDiscount.setText(discount);
        }
    }

Firebase

ReadWriteUserDetail class

public class ReadWriteUserDetails {
    public String birthday, discount;

    public ReadWriteUserDetails(){};

    public ReadWriteUserDetails(String textBirthday, String textDiscount){
        this.birthday = textBirthday;
        this.discount = textDiscount;
    }
}

You're storing your user profiles under path /Users/Customers in your database, so you can set up a reference to that parent node as:

DatabaseReference referenceProfile =
                         FirebaseDatabase.getInstance().getReference("Users/Customers");