This achievement is for gaining 5 million fans in MyCareer. Towards the end of the season, before the last game, I had just over 3 million fans. At the conclusion of the final game of the regular season, I checked the social media tab and had roughly 5,144,724 fans. I had also won the MVP award as well as many other various awards. I'm not sure how much these affect the number of fans gained but they seemed to give a large boost. Also, importantly, this achievement DID NOT pop until I finished my first playoff game. As soon as the first playoff game was over the achievement popped on my screen, and I was relieved as I thought the game had screwed me over. If there are any questions or clarifications needed just let me know.