Sending email with Workmail via Python

I'm trying to send email via Workmail using Python

import smtplib
from email.mime.text import MIMEText
from email.mime.multipart import MIMEMultipart
from email.mime.base import MIMEBase

def send_email(email_recipient, email_subject, email_message):
    try:
      server = smtplib.SMTP_SSL('smtp.mail.eu-west-1.awsapps.com', 465)
      server.ehlo()
      server.login('username', 'password')
      text = msg.as_string()
      server.sendmail(email_sender, email_recipient, text)
      print('Email sent to %s' % email_recipient)
    except Exception as e:
      print(e)
      print("SMTP server connection error")
    return True

def main():
  send_email('email@domain.com', 'hello', 'world')

main()

This does not work because

(535, b'Authentication credentials invalid')
SMTP server connection error

But using username and password, I am able to log into https://webmail.mail.eu-west-1.awsapps.com/workmail/ with these credentials.

So my questions are

1. Is it possible to send an email using the SMTP server of Workmail.
2. If yes, why are those credentials invalid (I also tried base64)

Many thanks in advance!