Container runner stuck on Preparing Environment

I followed container runner installation steps and finished all steps on an Linux EC2 instance. I am positive that I have installed container agent with the yaml configuration file that has access token in it. I also updated yaml in the code repo. The job triggered on CircleCI website, but it’s stuck on preparing environment forever. Anyone have any idea what’s potential issues? How can I debug and troubleshoot it? Any help will be appreciated, thank you!