NFL rules require the player placed on IR in the preseason to be on the 53-man roster at the start of the season in order to be activated for that same team that same season.
If a player is on the 53-man roster, he will be able to be activated and practice starting week 6 and play starting week 8. League rules have allowed ONLY one player per team to be activated from the IR list starting the 2012 season through last season (2016). Beginning this upcoming 2017 season, two players per team will be allowed to be activated.
So, that's the way the NFL rules are and Madden typically follows them pretty closely (at least on a simplified level). That being said, if you've "followed the league rules" and you still aren't able to play him, the game must not be recognizing it correctly.
Good luck!
