The sandbox is an environment in which you can test the integration between your application and Mediobanca Premier APIs.
In the sandbox, you will get test data from the APIs; in the production environment you will get live data and execute the operations for real.
You can request access to the sandbox anytime; to request access to the production environment you have to register as an AISP/PISP with your EBA-id and your EIDAS certificates (see also PSD2).