You cannot create sub accounts on your own. But you can add users, by taking the following steps:
1. Go to user management
2. Click "+ add" to add a new user
3. Fill in the email of the user who is going to be added
4. Click Invite user
A confirmation email with a verification link will be sent to the email address you just entered.
Clicking the link will redirect them to a page where they can create their account and continue to next screen or sign up with different credentials
A user must select a phonenumber for extra Two Factor security
A verification code is then sent to the mobile phone number given; entering this verification code validates both the email address and the phone number.
The new user can now start using the new account.