The administrators of an account (or failing that, users who have the necessary permissions) can add new users.
To add a new user, proceed as follows:
Open the menu at the top left
Select "Configuration" and then "Access management" in the submenu.
Here you have a view of all users who are linked to your domain.
Click on the "Add" button (if there are a lot of users, you will have to scroll down to reach the button.
Enter the email address of the person you wish to invite.
Configure access rights
To change access rights or completely remove access to a user's account :
Open the menu at the top left
Select the "Configuration" tab and then the "Access management" tab.
Here you have a view of all users who are linked to your domain.
Click on the pencil in front of the user to change his permission
Change permission
Save for the changes to take effect.