from selenium import webdriver
import time

driver = webdriver.Chrome()
driver.get("https://hcs.eduro.go.kr/#/loginHome")

driver.find_element_by_id('btnConfirm2').click()

time.sleep(2)
driver.find_element_by_css_selector('.input_text_common.input_text_search').click()

time.sleep(1)
elem = driver.find_element_by_id('sidolabel').click()

time.sleep(1)
elem.send_keys(keys.ARROW_DOWN) # <- [An error has occurred in this point and cannot be executed]