The end of season get-together was set to kick off preparations for the World Cup qualifiers, which begin with a double header against Serbia and Macedonia in September. Before then, Australia come calling in another friendly and McArthur is well aware that a major improvement is needed before the action begins for real.
The Wigan midfielder told Press Association Sport: "We just need to learn from it. We need to learn from the experience. We didn't play well enough and that's what it was down to."
He added: "The best teams in the world get beat. They learn from it and it makes them stronger so hopefully we can do that."
Scotland got off to the worst possible start when they found themselves two goals down with just 11 minutes on the clock.
Geoff Cameron turned a Kenny Miller header into his own net, which proved to be nothing more than scant consolation against a superior side who sit 19 places above the Scots in the FIFA world rankings.
McArthur added: "We didn't perform to our best. I thought they played well but, as a team, I didn't think we performed well enough on the night.
"I don't really know where it went wrong to be honest. It was just one of our off nights.
"Since the gaffer has come in, we have performed really well. It was an off night for us and it's disappointing. All the lads are gutted."