To integrate with EACAT you have to do it through the PCI.
The PCI is the Inter-administrative Collaboration Platform and has a generic messaging for all the services of the AOC Consortium, so you also need its documentation, which you can find here .
If you are not interested in just the simple submission, but have agreed with the AOC Consortium on a specific and more complex procedure, you will need the documentation available at the following link: https://github.com/ConsorciAOC/OVER
Once you have completed the integration in the Pre-production environment, you will have to fill in the docx ( Test games to be performed once you have registered for pre-production ) in order to validate the correct integration and formalize the transition to production.