Not getting username from Firebase database

My app is sending user name according to the below code

  mAuth.createUserWithEmailAndPassword(email,password).addOnCompleteListener(new 
  OnCompleteListener<AuthResult>() {
                @Override
                public void onComplete(@NonNull Task<AuthResult> task) {
                    if (task.isSuccessful()){


                        currentUserUid=mAuth.getCurrentUser().getUid();
                        FirebaseDatabase database = FirebaseDatabase.getInstance();
                        DatabaseReference myRef = database.getReference("MyUserList");
                        
  myRef.child(usernameInput).child(currentUserUid).child("username").setValue(usernameInput);

                        sendUserToLoginActivity();
                        Toast.makeText(RegisterActivity.this, "Account Created Successfully", 
  Toast.LENGTH_SHORT).show();
                        loadingBar.dismiss();

                    }

Now i have to get the username from Firebase database in another activity. I have tried the below way but every time the 'score' is passing to database but not the username. I don't want change the username setting way (above code) because i am checking duplicate username on user registration. How can i get the current username?

  private String currentUserUid;
  private FirebaseAuth mAuth;
  private String name;



  public void finisHere(){

       
        FirebaseDatabase database = FirebaseDatabase.getInstance();
        DatabaseReference myRef = database.getReference("Score");
         String key=myRef.push().getKey();

        //......................
        currentUserUid= mAuth.getCurrentUser().getUid();

        DatabaseReference cUserNameRef = database.getReference("MyUserList");

        cUserNameRef.child(currentUserUid).addListenerForSingleValueEvent(new 
 ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot snapshot) {
                for (DataSnapshot dataSnapshot:snapshot.getChildren()){
                   // String name="";
                    name=dataSnapshot.child("username").getValue(String.class);

                }
            }

            @Override
            public void onCancelled(@NonNull DatabaseError error) {

            }
        });
        savingScoreModel scoreModel=new savingScoreModel(score,name);
        myRef.child(key).setValue(scoreModel);
        Intent intent =new 
        Intent(liveQuestionActivity.this,MainActivity.class);

        Toast.makeText(this, currentUserUid, Toast.LENGTH_SHORT).show(); //Toast is working
        startActivity(intent);
        finishAffinity();


    }

i am verifying the duplicate user name by the below code.

  private  void DuplicateUserName(){
        final DatabaseReference rootRef = 
 FirebaseDatabase.getInstance().getReference();
        DatabaseReference userNameRef = 
 rootRef.child("MyUserList").child(usernameInput);
        ValueEventListener eventListener = new ValueEventListener() {
            @Override
            public void onDataChange(DataSnapshot dataSnapshot) {

                if(!dataSnapshot.exists()) {
                    //create new user
                    //Toast.makeText(RegisterActivity.this, "success", 
 Toast.LENGTH_SHORT).show();
                   /* FirebaseDatabase database = 
 FirebaseDatabase.getInstance();
                    DatabaseReference myRef = 
 database.getReference("MyUserList");
                    
 myRef.child(usernameInput).child("username").setValue(usernameInput);

                    */
                    CreateNewAccount();


                }
                else {
                    UserName.setError("This username already taken");
                    UserName.requestFocus();
                    loadingBar.dismiss();
                }


            }

            @Override
            public void onCancelled(DatabaseError databaseError) {
                Toast.makeText(RegisterActivity.this, 
databaseError.getMessage(), Toast.LENGTH_SHORT).show();
            }
        };
        userNameRef.addListenerForSingleValueEvent(eventListener);
    }

Username was Uploaded to "MyUserList"/usernameInput/currentUserUid/"username"

But you are fetching "MyUserList"/currentUserUid/"username"

So, try this for uploading:

myRef.child("MyUserList").child(currentUserUid).child("username").setValue(usernameInput);

Hope this helps. Feel free to ask for clarifications...

EDIT: Edited after @Farhad's doubts

DatabaseReference reference = database.getReference("MyUserList");

        reference.addListenerForSingleValueEvent(new ValueEventListener() {
            @Override
            public void onDataChange(@NonNull DataSnapshot dataSnapshot) {

                for (DataSnapshot singleSnapshot : dataSnapshot.getChildren()) {
                  
                    //TODO: Here are your UserNames

                    }

            @Override
            public void onCancelled(@NonNull DatabaseError databaseError) {
            }
        });