Attention!!! Anyone who's trying to install Assistant Relay currently from GitHub. There was a recent commit to the assistant relay github which broke authentication with the google assistant. Instead of using the the key file locations now, the latest version is using an OAUTH2 file method. If you are trying to install from @ogiewon's wonderful instructions, and clone from his fork of the Assistant Relay repo for installing version 1.0, you should not run into any problems and can follow the instructions exactly as written.
If you clone from the original fork to install AR v2.0, you have to modify the Google Assistant version from 0.6.0 to 0.2.0, otherwise, the rest of the program will not work correctly as there was no update for the Oauth2 method in the rest of assistant relay. So, in the instructions on page 15, after the git clone command, there is one thing that you have to do. You have to modify the package.json file. So, use a command like:
Then you have to change this line:
Then hit cntl-x and then save the changes. You should be all set after that. Just follow the rest of the instructions to finish installing.