OK. I think we're just misunderstanding each other here.
What Lieve is pointing out is that for any kind of Advanced Action to be executed (which is what you originally said you wanted to do once the user had entered their 6 digit number) then Captivate needs to have some kind of Event to use to execute the action. Unfortunately, just filling in a number into the TEB is not going to be seen as an Event. So the other two alternative ways of triggering something to happen are via the optional button that all TEBs can have, or via the Keystroke Shortcut (e.g. ENTER) that you can specify in the Shortcut field for the TEB.
Clicking a button to make something happen is sort of self-evident and most users would see the button and click it. But in most cases the user would not KNOW about the ability to use a keystroke shortcut unless you gave them some instructions. In TEBs you can use the Hint caption that appears when they mouse over the TEB to give them some basic instructions.
With TEBs you also have ONE extra option for triggering actions, and that's the ON FOCUS LOST event. This will trigger an action when the user moves their mouse cursor away from the TEB and clicks on anything else on the slide (including the TEB's button if you have one).
I get that you DON'T need to have any validation on the value entered into the TEB. But that's not really the issue here. The issue is HOW do you want to trigger that action? Which of the options I explain above is likely to be closest to what you want to happen?