iamzoli
With osTicket in order to see Tickets you have to have access to the Ticket's Department, you have to be directly assigned to the Ticket, your Team has to be directly assigned to the Ticket, or you/your Team has to have Referral access to the Ticket. Without any of these you will not be able to see Tickets.
You can also create an Organization, assign all needed Users to this Organization, add yourself as the Organization Account Admin, then enable the box for Auto-Assignment. Then, when any User in the Organization opens a Ticket you will be directly assigned automatically; in-which you will be able to see the Tickets they create without Department Access. Just keep in mind if you are assigned only and the Ticket is closed you will lose access to the Ticket as Assignment is dropped on Ticket Close. You can counteract this by enabling Auto-refer on close in the system settings. That way when the Ticket is closed it auto-refers to you and you can maintain access after closing.
Cheers.