From the evidence we have (emails about setting up the meeting), the alleged information (which, again, may not even exist) was about Hillary's dealings with Russians.
Information about such dealings would not have been on DNC servers, because such dealings (if they had occurred) would not have been done through the DNC. If there was evidence of that in her emails, they would have been on her servers, not the DNC. The DNC servers were hacked, but we have no evidence that her servers were hacked.
Furthermore, there's no reason to assume the information (if it existed) came from emails at all. If Hillary had dealings with Russians, then those Russians would have had record of those dealings, possibly even paper records. Russian intelligence could have obtained those records through lawful means, since they have jurisdiction over Russians in Russia. Hell, the information (if it existed) could have also come in the form of witness testimony.
But again, there's no evidence that the alleged information about Hillary ever existed at all, and non-existent information doesn't have a source.