options = webdriver.ChromeOptions()
options.add_argument("download.default_directory=/folder")
driver = webdriver.Chrome(chrome_options=options)

import webdriver
chrome_options = webdriver.ChromeOptions()
prefs = {'download.default_directory' : '/folder'}
chrome_options.add_experimental_option('prefs', prefs)
driver = webdriver.Chrome(chrome_options=chrome_options)

from selenium import webdriver
options = webdriver.ChromeOptions()
options.add_argument("--start-maximized")
prefs = {"profile.default_content_settings.popups": 0,
         "download.default_directory":
                    r"C:Usersuser_dirDesktop\",#IMPORTANT - ENDING SLASH V IMPORTANT
         "directory_upgrade": True}
options.add_experimental_option("prefs", prefs)
browser=webdriver.Chrome(<chromdriver.exe path>, options=options)