To send invitation email to employees, admins may

(1) Send to all employees
Under
People > Employee > click "Reinvite"
By clicking this, the system will send out invitation emails to ALL employees who have yet to activate their accounts.

(2) Send to specific employees
Under
People > Employee > search for employee in the search bar > click "Action" > select "Resend Invitation"
Repeat steps if there is more than 1 employee