EOS depends on Strapi for the configuration of the project and content management. We use GraphQL with Strapi to query our data. You can find more at the Strapi documentation and GraphQL Documentation
To setup EOS please follow the steps in our temporary documentation https://docs.google.com/document/d/1MB8LfV8eq96cPy7NDRKMkN1TT6gG1bkyfunnEaTGUrg/edit#
NOTE: We're working on a better documentation.