The easiest way to get this achievement is to pick one of the best teams in the league like Inter or AC Milan. Then set your difficulty to whatever you know you're able to handle, you can get the achievement on any difficulty. Easy is probably the best choice if you want to do it the easiest way. I also suggest not playing the cup, as that will take even more of your time, and you don't need it for the achievement.
Also to make it as quick as possible set the match time to 5 minutes and after you lead by two goals, steal the ball and then just stand there and keep the ball on the pitch. Everytime the ball leaves the pitch the time will stop and the match will last a little longer.
The whole league has 20 teams, you play each of them twice so that's a total of 38 matches. It's gonna take some time, but it's not really very hard. Just make sure you win enough games and don't lose too many points on being away. If you have enough points you still need to play the last few games to get the achievement. Should pop after the award ceremony.