In order for Travia to know the availability the rooms must be mapped between your channel manager (hotel system) and Travia.
When you are setting up the property in Travia you will be setting up your rooms as well.
When faced with this screen here:
Please set the number of rooms you have of this room type.
In order to connect the live availability to Travia, please select the Room ID and a dropdown list will appear with the rooms that this property has registered in your channel manager (hotel system).
When you have saved the room, the room is now connected to the live availability.