I get the same warning every time I start the game.
This is how I get past it, maybe it would help you too:
So you know that, when you run the game using the launcher, before loading the EA logo it shows you a black screen and your mouse cursor loading. There, when I see that black screen, I hit ctrl+esc or the Windows button. It doesn't react immediately, but eventually the game is minimized and I can see the Unofficial Game Modification Warning, which prompts me to quit the game. Therefore, I am also shown the option to "Continue".
Let me give you a screenshot of that pop-up...
Myself, if I hit "Continue", the popup disappears, and when I restore the game window, everything works fine.
Hope that helps ^_^