Please describe in one sentence what your goal is with smoothMQTT and then describe in detail, what you did with smoothMQTT after importing the asset to achieve that.
for example:
I want to show temperature data from a sensor in a UI text element in Unity.
After downloading and installing smoothMQTT, I started a new scene, added the MqttManager to the scene. I switched on debug mode and added the host IP (external Mosquitto broker) in the settings component. After that I added a UI text object to the scene. I also added an empty gameobject, selected it and chose "Receive -> String Payload" in the Tools menu. Lastly I added a topic "test/topic" and an action to the new subscriber component that uses the text property of my UI text object to set the text.