Of course he was talking to the Church, Of course the Holy Spirit is speaking today. But read the book of acts naively and see that always the Way was taught by people OF AUTHORITY. And how did they acquire that authority? By association with those who are presented in Acts as having authority, those, in other words, who were inspired. The Word leapt from person to person, most often by people steeped in the JEWISH Scriptures AND inspired by God. We do not know what taught Apollos—Scripture doesn’t say— but SOMEONE did, and his teachings were sanctioned by someone who know was inspired by God,that is Paul. And according to Acts, Paul who claimed to an independent revelation of truth nonethless always went back to the Church to report and to substantiate that his words were those of the Church and so were the words taught in the church communities he founded.
Actually, it was the other way around after a very short time. There was general agreement among the body, but Paul had to rebuke both Peter and Barnabas when they faltered. That is what the church is: believers bouncing their beliefs off of each other to see who is heading astray. The written word is the only "authority" we have, and all must be held to that standard.