Event when signing up

Hello everyone
I am trying to trigger an event via rocketchat apps when a new user signs up. I will be using the event to create relevant data strcutures and other user data in my external application. Is there anyway to get this event through rocketchat apps?
I was looking at event interfaces here, but didn’t find any event to handle the scenario I am looking for.

This feature may be useful as I am trying to connect a bot framework using apps (Not looking to implement hubot, botkit etc as I would have to host my own server for bot framework). I would like to send a welcome message to user when they sign up preferably using apps.

Thanks in advance.