I had to click on the body for the Keys.PAGE_DOWN to work but didn't need to use the action chain:
from selenium.webdriver.common.keys import Keys
body = driver.find_element_by_css_selector('body')
body.click()
body.send_keys(Keys.PAGE_DOWN)
from: https://stackoverflow.com/questions/39471163/selenium-page-down-by-actionchains/39472743