This must have been a claim that Carter Page was the "agent" of the Russians Sechin and Diveykin in the Steele Dossier where it was claimed that Page would try to lift Russian sanctions in exchange for payment from the Russians.
But as we know from Snowden and other whistleblowers, the FBI and the US intelligence agencies have so much information on what's going on in the world that the FBI probably knew themselves from other technology there was no such meeting with Carter Page and these Russians and pretended otherwise just so they could spy on Trump people.
Exactly. Like a cheater who has stollen the answers to the exam questions ahead of the exam, the FBI has access to all the raw intel on everyone, courtesy of the NSA. When they need to "get" someone, and everyone is guilty of breaking *some* law, the FBI just pulls the "answer" from the NSA data. Then it creates the legal fig leaf of going thru whatever motions are still required to preserver the illusion that the country operates under a law of checks and balances with peoples' rights preserved.
Thru Hillary, the FBI was obsessed with spying on the Trump campaign. The FBI pulls the raw intel and finds... nothing of substance to use as a pretext. Apparently the best they could find was Carter Page talking to a Russian. But you can't go to the FISA court and say you need to wiretap the guy based on your wiretap info from the guy you want to wiretap. Doesn't look good. So they unearth the article in Yahoo news as their non-wiretap "source".