It is always +1 bag to what is already included in your fare.
On a light economy (no baggage) you get 1 free bag.
On standard economy you get 2 bags.
After purchasing the ticket you should be able to see correct number of free bags when you log in to manage your trip.
As DL platinum you can select any economy seat for free, including exit rows.
as opposed to KLM, AF planes do not have any comfort economy seats at all.