The indictment lists 31 documents that certainly going to be part of discovery.

Just found a good explanation of how cases like this work.

Before the trial CIPA applies

In such cases, a 1980 federal law known as the Classified Information Procedures Act is supposed to balance the government’s interest in maintaining secrecy with a defendant’s right to a fair trial. ...

In this same pretrial period, any defense lawyers who don’t have security clearances will need to get them. The FBI’s background check process can take many months, so if prosecutors worry about excessive delays, they can urge the FBI agents to speed things up. Defendants can also try to find lawyers who are already cleared. .... Once classified documents are determined to be included in the discovery material, defense lawyers can view the classified materials in a sensitive compartmented information facility, or a SCIF.

Apparently the courthouse doesn't have a SCIF, but a building close by does.