var TextBoxElement = win.FindElement(By.XPath(".//*[@ClassName = 'PasswordBox' and contains(@LocalizedControlType, 'поле')]"));

var TextBoxElement = win.FindElement(By.XPath("/Pane[@Name="Рабочий стол"][@ClassName="#32769"]/Window[="Наименование приложения"][@ClassName="Window"]/Tab[@ClassName="TabControl"]/TabItem[@Name="Подключение"][@ClassName"TabItem"]/Custom[@Classname="CredentialBoxControl"]/Edit="PasswordBox"]"));