Paul is elsewhere when Priscilla and Aquila run into Apollos at Ephesus. It is fascinating that Acts now shifts to putting Priscilla first. Acts mentioned Aquila first at their first encounter with Paul, maybe because he was more the tent-making guy. But now, when it comes to teaching Apollos about Christ, Acts mentions Priscilla first. Was she more the leader when it came to spiritual things?
Apollos is well-educated, from a university town, so to speak. It is perilous to pick someone as the author of Hebrews--we just don't know. But he sure seems like the type of person to have written Hebrews. Here's a guy who would have known of Philo in Alexandria and known a bit of the way he used Scripture.
Apollos fits in a category we will also see at the beginning of Acts 19. He has heard about the John the Baptist movement out of which the Jesus movement came. He has heard that the Lord is coming, understood to be the Messiah. But he didn't know about Jesus and he didn't know about the Holy Spirit.
Priscilla and Aquila take him under their wings. They share the rest of the story. Apollos believes. I would presume he would be baptized and would receive the Holy Spirit, although Acts doesn't tell that part.
He goes back to Corinth, where I suspect he teaches things a little differently than Paul and soon finds himself at the center of an argument between factions in the Corinthian church. His followers say, "But Apollos said we don't need to worry because idols don't really exist." Paul's core say, "But we shouldn't eat at a pagan temple." This was 1 Corinthians in the making...