The Wallabies take on Argentina in San Salvador de Jujuy on Saturday and then Mendoza one week later as they continue their preparations for hosting the World Cup.
“We’re coming up against a good Argentinian side, who we've had some great battles with in the past,” Donaldson told a press conference in Buenos Aires on Tuesday shortly after the squad's arrival.
“It's definitely vital, leading into a pretty big year next year, that every game is big for confidence, for cohesion and just getting a bit of belief.
“Every away trip, especially in Argentina, is massive but, in saying that, we've just got to focus week to week as every week is big for us leading into the World Cup.”
Australia have played five tests this year and there are nine more by the end of November, plus more preparatory games to come next year ahead of the Wallabies’ opening World Cup match against Hong Kong in Perth on October 1, 2027.
“Every game has great weight and every time we put on the jersey, we go out there and do our best job, and it starts this weekend. It's going to be a great challenge for us,” the 27-year-old added.
It will be a third game under new coach Les Kiss, whose opening two matches in charge against Japan delivered a narrow 35-32 away win on August 8 and then a convincing 56-17 home victory in Townsville a week later.
Kiss has looked to put his stamp on the team after taking over from Joe Schmidt by demanding more direct attack.
“I've been really enjoying it,” said Donaldson, who came off the bench to play around 20 minutes in both tests against Japan.
“It's a fine balance between trying to play with more width, throwing the ball out a bit more but also trying to play through them, being direct at the same time,” Donaldson said.
“We're just trying to find our balance at the moment. You know, we can't go wide all the time.
"You’ve got to play direct, play through them to start the game, but personally as a fly-half, I like a bit more width in the game, gets us No. 10s in the game a bit more and opens up a bit more space for outside backs.
“So, personally I've been enjoying it and I think the boys have as well,” he added.