首先，该按钮没有id='button'
没有看到该网站，你可以尝试这样做：

login_button = driver.find_element(By.TAG_NAME, 'button')
login_button.click() # this assumes that there are no other buttons on the page as find_element finds the first button on the page

或

login_button = driver.find_element(By.CLASS_NAME, 'btn')
login_button.click() # this assumes that there are no other elements with the `btn` class to click