question

To implement your requirements, you need to keep the field “CreateAccount” of login API such as LoginWithAndroidDeviceID as “true” and do the API call in the Unity Start() function. Besides, you should add the judgment for the response of login API, if the value of “NewlyCreated” is true, it means it’s the first time for the player to enter the game, the player needs to provide the username, email, and password, and you should call the API AddUsernamePassword to submit the information. If the value of “NewlyCreated” false, it means it’s not the player’s first login, the player can enter the game directly. You can refer to the document -- Login basics and best Practices - PlayFab | Microsoft Docs for more information about best practice of integrating anonymous login and recoverable login.

The possible code sample could be something like this.

using PlayFab;
using PlayFab.ClientModels;
using System;
using UnityEngine;
using UnityEngine.UI;


public class LoginSample : MonoBehaviour
{
    public InputField UsernameInputField;
    public InputField EmailInputField;
    public InputField PasswordInputField;


    void Start()
    {
        var request = new LoginWithAndroidDeviceIDRequest { AndroidDeviceId = "GettingStartedGuide", CreateAccount = true };
        PlayFabClientAPI.LoginWithAndroidDeviceID(request, OnLoginSuccess, OnFailure);
    }


    private void OnLoginSuccess(LoginResult result)
    {
        if (result.NewlyCreated)
        {
            //Display InputField UI
            var addUsernamePasswordRequest = new AddUsernamePasswordRequest { Username = UsernameInputField.text, Email = EmailInputField.text, Password = PasswordInputField.text };
            PlayFabClientAPI.AddUsernamePassword(addUsernamePasswordRequest, OnAddSuccess, OnFailure);
        }
        else
        {
            //Enter the game logic
        }
    }


    private void OnAddSuccess(AddUsernamePasswordResult result)
    {
        //Enter the game logic 
    }


    private void OnFailure(PlayFabError error)
    {
        Debug.LogError(error.GenerateErrorReport());
    }
}