Bjelis: I think that I'm not that bad in the game but seems to me a little bit unrealistic to see some players have an average score about 60, ohh boy that's so unreal :D
Well, a 60 average is not that "unreal" in this game. Some players have been doing this 10 years.
Remember too, that averages are relative only to the tier that a player is in. Every time someone tiers up, the calculation of the average starts over - and the game gets harder each tier.
I had a 62 average before tiering up last time. Then I had to move back to the longest tees and the green speeds got faster. I am a better player now, but my average is about 5 shots higher than then.
This game takes time.
As to credits, you can (1) buy them, (2) win them in tournaments, (3) get them free through the videos and surveys set up for that.