Go to setup (via the gear icon in the navigation bar) and select users in the left menu.
Press 'add user' to add new users. Set one or more user roles at the bottom of the pop-up screen.
If a new user is added, the person will receive an email with login instructions on the email address that is entered for the user's account.
Do you want to grant a user's account all permissions? Set the user roles 'administrator' and 'planner'.
Depending on a user's responsibilities and skills, there are different user roles.