On a local level, seized documents would be transferred from location to agency after service of a warrant.
In this case, with the amount of docs seized, it's plausible that docs stayed in place during investigation and are now being transferred. Either for safe keeping or for congressional hearings.
If this was a normal federal case these docs, as evidence, would go to the court of original jurisdiction (AR Fed court).
However nothing about this case is normal.
Further local level process:
After seizure, Docs would be reviewed by law enforcement entities, a DA packet created outlining evidenciary significance of any evidence therein, and handed off to DA's office for prosecution.
Copies would go to DA's office for court room use while the originals are stored at law enforcement agency with original jurisdiction.