Good news.
That eerror indicated the AutoRemote was either not configured properly and/or not running. One of the Tasker profiles supplied is supposed to start AutoRemote automatically in the proper mode when running THR.
Have you examined the “Getting Starteed” documentation in AutoRemote? (open up AutoRemote explictly, tap on the three vertical buttons at the bottom, then tap “Getting Started”)
Note that AutoRemote receives messages in two ways, a secure method and a non-secure method. The method used by the THR plugin uses the non-secure method, and therefore it is a good idea to only run AR when actively using it. AR does reset itself on reboot to automatically protect the user.
I have attached a test Tasker routine I used to verify AutoRemote was working without having to involve THR. Remember to rename the attachment from .txt to .xml before importing into Tasker. If you open up the task, you can also see how HTTP requests are made from within Tasker.
HRTest.tsk.txt (9.1 KB)