who knows man I like this game but I didn’t really wanna replay it so I have been looking it up but it’s apparently a state secret
Just follow the timeline until you don't have side quests. I played last update and that meant challenging Rita was one of the last things I did. You also just die if you challenge her too soon. You either win or game over. Just save before you think about challenging her. I believe you get a hint in game when you are ready but i played months ago.