It needs to be installed in a virtual python environment. FireTV server runs on Python 2.7 and HomeAssistant requires Python 3.
This thread might help you in setting it up in a virtual environment.
I am able to see my FireTV’s in the media player without it, but I’ve considered installing the FireTV server to see if the support is better.
It’s a to do project that I haven’t gotten to yet, but once I do I plan on writing a tutorial for it.