Ryan said it will take time to adapt to what Postecoglou wants to enforce, and how the former Melbourne Victory boss demands the team to approach their football as they prepare for Thursday's friendly with Belgium in Liege.
It is Australia's first international appearance since their World Cup campaign, which saw them lose no fans despite a point-less group stage.
Postecoglou has been in the top job since October.
"We had a little review form the World Cup yesterday, just going over different things. [Postecoglou] wants us to have more belief in the system and those sorts of things," Ryan told FFA TV.
"We all tried to buy into it but it's not until you get the regular games where you can make mistakes in terms of learning what he really wants from us in every situation.
"You can't help but think if we had had another 12 months together as a team [before the World Cup] how different things could have been."
Given the way the Socceroos performed at the World Cup, Ryan said he is confident the side will continue to improve the more the youthful squad plays together.
"The progress we’ve been making has been coming in leaps and bounds," the former Central Coast Mariners man said.
Ryan, who played all three matches at the recent FIFA World Cup in Brazil, has been Postecoglou's first-choice goalkeeper.
The 22-year-old has earned that spot, having been in fine form for Club Brugge as he took out the Professional Footballers' Goalkeeper of Year gong in Belgium last season.
But the keeping position is one with a great deal of options for Postecoglou to ponder.
Mitch Langerak is now playing more regularly at Bundesliga giants Borussia Dortmund while shot-stopper Adam Federici is now first-choice at Reading once more.
A-League stars Eugene Galekovic and Mark Birighitti are also in the mix after being in the original travelling party that went to Brazil.
"There's great competition for every spot in the team at the moment," Ryan said.
"I don't think any position on the team should be safe at any time in one's international career. If you're playing well and you deserve the right to have the spot, that's the way it should go.
"The likes of Mitch [Langerak] and I see Adam Federici is playing more regularly now, it's good for them personally and they get to develop also.
"For myself I just focus on coming in here and trying to work hard. Fingers crossed it can be me out there come game time."
