If you can't find the terminal in the RDU manager:
1. If it is visible in the website check if there is a company card assigned to the terminal
Then edit the terminal and delete the assigned company card to the terminal, after this restart the client application.
2. If you can't see the terminal in the web page then open a ticket here and ask someone why you can't see the terminal.
-There are two possibilities for this, the terminal was deleted or it wasn't assigned to your company