This is an acheivement you get as you progress your pro PGA Tour career. From the Road to the PGA Tour section, below event schedule is EA Sports Golf Rankings. You rank up as you do well in tournaments.
I have the Masters edition, no DLC, won and played in all tournaments (quite a few won't let you in at the start as you are not in the top 100) and this unlocked after you win your 12th event, the BMW Championship. After you win the Barclays (11th event) you will actually be in the top 50, but the achievement won't pop until after the BMW, by which time you will probably be in the top 40.
That said, this can be a bit glitchy as and when it unlocks - see comments below as for some it unlocks after the Barclays.