issue while Login to TextNow using selinium tool Automation

I'm trying to automate TextNow using selenium automation tool but when i'm trying to add Username and password after automation getting an error of Username or Password is invalid and same is working fine manually.

below is the code which i tried

 static void Main(string[] args)
        {
            IWebDriver driver;

            driver = new ChromeDriver("cromepath");
            driver.Url = "https://www.textnow.com/messaging";
            driver.Manage().Window.Maximize();
            IWebElement userName = driver.FindElement(By.Id("txt-username"));//txt-password
            IWebElement password = driver.FindElement(By.Id("txt-password"));

            userName.SendKeys("username");
            password.SendKeys("password");

            IWebElement login = driver.FindElement(By.Id("btn-login"));
            login.Click();


        }