Aren't you confusing "the zohar" with "kaballah?" You asked why Chaim said the Zohar was written a few hundred years ago and then went into a big thing about Adam and Yaakov etc receiving prophesy (and presumably kaballah/Torah secrets). But the Zohar is an actual text that indeed was written at a certain date. It contains kaballah, but why do you presume that the full extent of kaballah is limited to what is written in the text the zohar?