If you want to automatically reply to messages based on a pre-determined keyword, you can use the simple chatbot feature.

Just follow the steps in the image below.

Additional notes:

1. Make sure to enable the chatbot feature (refer to step #8 above)
2. You can set multiple keywords
3. Select the appropriate type of autoreply.
   1. "Message contains the keyword" means exact match
   2. "Message contains the whole keyword" means as long as the keyword is detected, the system will autoreply