As the account administrator, you have the ability to add new users to your Console according to the number of open licenses you have.
1 - Access to your Console
From the Manage my team (available by your profile picture), click on the "Users" tab and on 
2 - Fill in the form
Email address, surname and first name) then select the role of your choice (PRO licence or FREE account).
3 - Click on send an invitation
The guest will receive an invitation email to join your Console and activate their account.