What is RCS for?

RCS is datapack, that adds recipes for some stones which are in Create mod. These cannot be farmed without datapack. So for example you can build automatic zinc farm with RCS!

Has RCS any requirements or limitations?

You need Create mod.

Why is there different version for Fabric and Forge?

It's because Fabric and Forge use different "units" of fluid. I cannot set unit in datapack, so there have to be two different versions. Specifically, Forge is using milibuckets (1000 mB = 1 bucket), but Fabric is using droplets (81000 droplets = 1 bucket)

Fell free to include this datapack in any modpack!