To unlock this achievement you must reach the final level of the season progress objective in Ultimate Team. For season one this is level 40. Pay attention to live objectives that offer significant xp for completing them and be sure to do the seasonal weekly objectives for good xp. You also get good xp for competing in Fut Champs.
WARNING: I recently got to level 40 on my series x and unlocked the achievement. I then logged in on old gen hoping the achievement would unlock there too and it's doesn't seem to have. I will try a few different things but at the moment it seems like you might need to do this one twice for current gen and old gen.
UPDATE: I completed another xp related challenge on my old gen and the achievement unlocked about 2 minutes after. So you to need to earn more xp on the other generation to get it to pop again.