To find your username, it's simple!
Your username is usually structured as follows :
COMPANYNAME/first letter of your first name + last name
Example: If I work at HelloCSE and my name is Marie Dupont
Username : HELLOCSE/mdupont
Your account may have been associated with an email address during registration.
First, I suggest using your professional email address.
If that doesn't work, you can try your personal email address.