Per Barr, Mueller’s report said that no American colluded with Russia to affect the election. So, if that is true, Seth Rich did not pass the emails to WL.
Since the DNC never submitted the servers to FBI forensic investigators, the Mueller report could not possibly determine whether the servers were hacked by Russia or whether information was downloaded onto thumb drives. Unless the SC had undisclosed access to the servers, we will hear much more about this during the investigation into Spygate.