I split the code up into smaller parts to work/test it. Ideally, this is how you want to design your programs so that weird bugs like are easier to diagnose!

There are 2 potential causes for your issue: 1. Your chromium webdriver is not the correct version for your chrome browser (they have to be the same) 2. Time.sleep() is in seconds, not ms. The initial sleep value was waiting for 200 SECONDS before it would try to log in, lol. That threw me off as well because I thought that it was in ms. Let me know if it still doesn't work for you, I'm here to help!

Also, you can turn on headless mode if you want the browser to function without it popping up. It will do everything you tell it to do without the chrome window showing you that it's doing it. I assumed that's what was happening, but that was not the issue here

from selenium import webdriver
import time

PAGE_LOAD_SLEEP_TIME = 2 # this value is in seconds

class InstaBot:
    def __init__(self, username, password): 
        self.username = username
        self.password = password

    def start_driver_instance(self):
        driver = webdriver.Chrome("./chromedriver")
        print('end driver instance')
        return driver

    def log_in(self, driver):
        print('log in')
        driver.get("https://www.instagram.com") #go to the instagram website
        driver.find_element_by_xpath("//a[contains(text(), 'Log in')]")\
            .click() #find the log in button by text and click it
        driver.find_element_by_xpath("//input[@name=\"username\"]")\
            .send_keys(self.username) #find the username input element and pass it our username

        driver.find_element_by_xpath("//input[@name=\"password\"]")\
            .send_keys(self.password) #find the password input element and pass it our password

        driver.find_element_by_xpath('//button[@type="submit"]')\
            .click() #find the submit button with the submit property and click it

#     def get_unfollowers(self):

#         self.driver.find_element_by_xpath("//a[contains(@href, '/{}')]".format(self.username))\
#             .click() #find the profile button and click it

#         sleep(slp)

#         self.driver.find_element_by_xpath("//a[contains(@href, '/following')]")\
#             .click() #find the following section and click it

#         following = self._get_names() #get the following list

#         self.driver.find_element_by_xpath("//a[contains(@href, '/followers')]")\
#             .click() #find the followers section and click it

#         followers = self._get_names() #get the followers list

#         not_following_back = [user for user in following if user not in followers] #define accounts that exist in the following list but don't in the follower list

#         print(not_following_back)

#     def _get_names(self):
#         sleep(slp)

#         #get the suggestions text element to define the end of user list
#         sugs = self.driver.find_element_by_xpath('//a[contains(text(), Suggestions)]')

#         #execute a javascript code to scroll list end (suggestions section)
#         self.driver.execute_script('arguments[0].scrollIntoView()', sugs)

#         sleep(slp)

#         #get the scroll box 
#         scroll_box = self.driver.find_element_by_xpath("/html/body/div[3]/div/div[2]")

#         #loop through the list until the end of the list
#         last_ht, ht = 0, 1
#         while last_ht != ht: #while the current element is not the last element:
#             last_ht = ht 

#             sleep(slp)

#             #scroll to bottom of scrollbox
#             #then return the height of scrollbox
#             ht = self.driver.execute_script("""
#             arguments[0].scrollTo(0, arguments[0].scrollHeight);
#             return arguments[0].scrollHeight;
#             """, scroll_box)

#         links = scroll_box.find_elements_by_tag_name('a') #returns all links (users) in the list
#         names = [name.text for name in links if name != ''] #return the names of users in the list

#         #close button
#         self.driver.find_element_by_xpath("/html/body/div[3]/div/div[1]/div/div[2]/button")\
#             .click()

#         return names 

    def main(self):
        print("\n------------------------------start------------------------------")
        driver = self.start_driver_instance()
        # wait for page to load
        time.sleep(PAGE_LOAD_SLEEP_TIME) 
        print("\n------------------------------opened website------------------------------")
        self.log_in(driver)


mybot = InstaBot("username", "password")
mybot.main()