Hi @Ams,
You should be able to have access to it. You can schedule as session here so that the team can help you look it. http://tiny.cc/FIRMBS
However, as a System Integrator, you do not need your keys to implement. You are expected to collaborate with a taxpayer to test your implementation. In this setup, the taxpayer will provide you with their Business ID, Service ID, Keys, and other required parameters for integration and validation.
Alternatively, if you are also registered as a taxpayer, you may enable your own business for e-Invoicing and use your credentials for the implementation and validate your integration flow.