Carbon assembly paste is designed for carbon. It’s grease like stuff with small particles that provide friction. Never had an issue getting an ali post in a carbon frame using the stuff and the paste means you don’t need to clamp as tight.
As for the corrosion, it’s galvanic reaction between two dissimilar materials. Carbon assembly paste helps reduce it, but I’ve found it can still happen. Just that with the paste the seatpost didn’t bond to the frame as severely as it did originally without the stuff where it took a hell of a lot of effort, tools, vice and swearing to remove it.
Also a few post manufacturers recommend using the paste for ali frames also. There are differences between types of ali which can still result in a reaction, plus the paste help reduce the clamping force required.