So you want your RightBooth users to enter one or more coins into a coin acceptor before they are allowed to use your event.
What you need to do is to find a coin acceptor solution that can generate and send a chosen keystroke into the Windows keyboard input subsystem, usually via USB keyboard emulation. With this solution, the keystroke will be sent each time a predefined coin (or combination of coins) are inserted into the coin acceptor.
There are many coin and bill acceptors available, but most of them require additional hardware to allow you to connect them to the PC and generate keystrokes. However, there are ready made solutions available where others have done the heavy hardware lifting for you, such as this product:
Or if you are feeling more adventurous, you could experiment with solutions like this:
So once you have your coin acceptor working and connected to the PC, here is the change you need to make in RightBooth:
Now when you play the event, RightBooth will wait at the Start screen until a coin is inserted into the coin acceptor, at which point it will progress to the next screen in your event, allowing the user to access your event features. And at the end of each user session, RightBooth will return to showing the Start screen, waiting for the next user to enter a coin into the coin acceptor.