Hey there!
Firstly, thank you very much for your review! Hopefully TicketManager is able to replace your previous setup!
Regarding the ticket messages on login, the plugin supports both of your requested features! These features require certain permission nodes. For staff to see the number of open tickets on login, use ‘ticketmanager.notify.openTickets.onJoin’. For players to see which of their tickets have changes on login, use ‘ ticketmanager.notify.unreadUpdates.onJoin’.
All TicketManager permissions are listed at
https://github.com/HoshiKurama/TicketManager/wiki/TicketManager-8-Permissions. If you have any other general questions though, feel free to join the Discord server and ask them!