So when (hote oun). Transitional use of oun, sequence, not consequence.
Received him (edexanto auton). First aorist middle of dechomai, “welcomed him.” Jesus had evidently anticipated a quiet arrival.
Having seen (heōrakotes). Perfect active participle of horaō. Note theōrountes in Joh 2:23 about this very thing at the feast in Jerusalem. The miracles of Jesus at that first passover made a stir.
For they also went (kai autoi gar ēlthon). The Samaritans did not go and so Jesus was a new figure to them, but the Galileans, as orthodox Jews, did go and so were predisposed in his favour.