if you don't have php installed, make sure to do so. on macOS if you have homebrew, you can just brew install php
Run in main experiment directory:
locally: php -S 127.0.0.1:8000 -t .
on a server: php -S 0.0.0.0:8000 -t .
then if running locally, go to http://127.0.0.1:8000 if on a remote server, http://:8000