Hopefully if you go to each fan and follow its cable, there should be the standard 3pin or 4pin connector.
You may find it goes into an adapter to a) extend the length so it reaches your RGB controller, and b) that allows it to get converted into the type that goes onto that controller.
You may find it goes into an adapter to a) extend the length so it reaches your RGB controller, and b) that allows it to get converted into the type that goes onto that controller.