I ran into trouble trying to get the plugin working on an M1 (Silicon Chip) Mac. The problem was with the pyatv & cryptography libraries. To solve:
I had to upgrade to python 3.9 and upgrade pip3 to the latest version (As of now Pip3.9).
Then I created a new terminal app to run in rosetta Mode(right click and duplicate Terminal in the Finder, rename to RosettaTerminal, right click get info, and check option to "Open using Rosetta").
Install anaconda 3.9 through their website.
https://docs.conda.io/en/latest/miniconda.html Launch Rosetta Terminal
Finally install cryptography in the rosetta terminal using
python3.9 -m pip install --upgrade --no-use-pep517 cryptography
and then
pip3.9 install pyatv
Once this was done, I changed the python path in the plugin configuration to my python3.9 install location and my Apple TVs connected.
Tested successfully. This issue has been resolved for me.