Chapter 22 is one of those chapters that doesn’t begin “cleanly”, in the sense that there’s a new section or topic or event. It simply continues on from what was happening at the end of chapter 21. (And again here’s a reminder that the chapters and verses were not part of the original texts. The earliest appearances of chapters and verses began in the 10th century AD, though some “sectioning” of the text is evident already in the 4th century. Chapters and verses in the whole Bible as we know it today weren’t produced until the time just after the Reformation, in the mid-16th century AD. Though not arbitrary, we don’t consider them part of the inspired, inerrant Word; they’re simply helpful in considering shorter pieces of text, for example in memorizing or reading in public.)
22:1-2 It might be most helpful think about 22:1 simple as an extension of 21:40b:
“And when there was a great hush, he addressed them in the Hebrew language, saying...”. This helps gives us good context for what Paul actually says, and whom he is addressing.
The audience for this speech of Paul’s is a Jewish one, and so the fact that he’s speaking to them in Hebrew is significant. There is at least a modicum of respect for that, that this person who seems to be upending Jewish customs (see 21:20-22 and 27-29).
22:3 Paul begins his answer/defence (the Greek word used in 22:1 is apologia, which is where we get our English word apology from; it doesn’t mean “I’m sorry”, but literally “a word from”, meaning “a defence” “an answer to”) by giving his Jewish credentials. As we know from other places in the New Testament, most notably his letters/epistles, Paul was a Pharisee (e.g. Philippians 3:4-6), having studied with a teacher who would have been well-known among the crowd: Gamaliel.
22:4-21 Here Paul recounts what we have previously heard about in Acts 8 and 9, and here we get some personal recollection that Luke didn’t include earlier (e.g. verses 17-19).
22:22-24 The scene is reminiscent of the day of Jesus’ crucifixion as the crowd, instead of accepting Paul’s defence, continues its mob mentality and calls for the death of Paul. But instead of the Roman official giving in to the crowd, as Pilate did for Jesus, the tribune here brings Paul in to be interrogated according to Roman custom.
22:25-29 The problem for the Roman officials, though, is that they acted in haste and without due process. Paul was a Jew, yes, but because he was born in Tarsus, he was a Roman citizen by birth, with a stronger claim even than the tribune who was in charge of his imprisonment. Roman law forbade a Roman citizen to be treated like a non-citizen, and the tribune was doing exactly that. So he’s rightly afraid when he finally learns the whole story about Paul.