I'd like to write code for login this page,

So in order to be able to interact with the login form, we first have to switch to the iframe by running the following code

from selenium.webdriver.support.ui import WebDriverWait
from selenium.webdriver.support import expected_conditions as EC
WebDriverWait(driver, 20).until(EC.frame_to_be_available_and_switch_to_it((By.ID, "loginFrame")))

After this you can run the code email_input = ... and click on the element