If you are not receiving any Hunter Express rates using your own Hunter Express account credentials, turn on debug to analyze the results.
If you can see this message:
[message] => Bad credentials
[status] => UNAUTHORIZED
You will need to reach out to Hunter Express and ask them for Hunter Express shipping API account credentials.
The Hunter Express shipping API Username, Password & Customer Code are different than the customer account credentials used to log into the Hunter Express website.
*This is what we found when testing and building the plugin for a client.