N.K.
Dear C.,
I would start wioth just opening it up outside and pulling all the parts out of the bag.
You can was the bag and hose it off as it is waterproof and easy to clean.
Leave the pieces outside overnight and then wash them with a buicket of warm water with somthing like 409 mixed with water.
If it still smells you could also then spray it with antimicrobial Febreze.
We had some camping gear that smelled moldy and this did the trick.
N.