Getting to CDG with engineering works on RER

Hi, I have a flight from Charles de Gaulle on Friday 25 at 5pm. I arrive into Bercy and have about 3 hours to make the transfer :) . I was considering stopping for lunch but I have this travel update on the suggested route from Google : ‘Line B: interconnection suspended on 25-26-27/10 · Period: all day Dates: from Friday 25 to Sunday 27 October 2024 For the day of Friday 25 October, we strongly recommend that you postpone your trip. Interconnection will be suspended in Paris North. To continue your journey, a train change will be necessary between the underground tracks and the surface tracks. The trains in the direction of CDG2 Airport and Mitry-Claye will leave from the surface tracks, tracks 30 to 36. Trains heading to Robinson and Saint-Rémy lès Chevreuse will leave from underground tracks, tracks 41 to 44. Reason: works For more information, consult the RER B blog.’

It all sounded a bit complicated so I was considering getting the Roissy Bus but I can’t figure out where it is going from? What is my best option? I don’t know Paris well.