Scotland bounced back from a 24-8 defeat at the hands of the Welsh in the pool stages of the championship in Mendoza.
Shade has been providing video analysis for the squad.
Scotland U21 captain Neil Cochrane said: "The result we wanted was coming. The guys worked hard for the win and they deserve it after the Six Nations and last week's game. There was a real hunger in the squad.
"We have done a lot of analysis work with Shade Munro, who has been excellent for us out here. That helps us pin-point other sides' weaknesses and also lets us see how we have played.
"Our defence was key for us last night as we didn't let them run at us like they have done in the past. Wales are formidable opposition but we stuck to our guns and came away with the right result," he added.
Scotland take on hosts Argentina on Saturday to determine fifth and sixth place. No matter what the outcome of that match, the Scots know they will finish the highest out of the four home nations.