Dude, you clearly haven't been following the news headlines much at all. I know you're not a stupid person, so the only excuse here is lack of knowledge of the story. It is common knowledge - reported by the Washington Examiner and others - that the Flynn interview was a set-up by McCabe and Strzok (both of whom have been fired). They lulled Flynn into thinking that they were just having a regular conversation about national security and told him not to have an attorney present.
Also, the interview happened in mid-January 2017, right around the time that Trump was inaugurated. So Trump had no influence yet on the FBI, and, in fact, even to this day he does not have much. The DOJ and FBI are still populated by anti-Trump holdovers. That is plain as day. So calling it a "Republican-influenced FBI" is preposterous. Chris Wray (the new FBI director) does not at all appear to be aligned to Trump.
Third, and most important, what Flynn did on his call with Kislyak was nothing irregular for an incoming national security adviser. They all have talks with foreign officials during that time. Michael Flynn is not the first to have done that.
But here is the actual story on Flynn, from the Washington Examiner:
"The interview was set up directly via a phone call to Flynn from Andrew McCabe, who then was deputy director of the FBI. McCabe, by his own account, made it sound like an ordinary national-security-related briefing of the sort Flynn was accustomed to giving the FBI. Even though McCabe clearly knew that Flynn was a potential subject of investigation, he deliberately dissuaded Flynn from having attorneys present."
https://www.washingtonexaminer.com/opinion/fbis-entrapment-of-general-flynn-was-despicable