I got this off the chessok website:
Rybka 3 is UCI engine, meaning that it can be taken from Aquarium and connected to any chess program, supporting UCI protocol, like Fritz (Chessbase) or Arena.\
I think if you go to engine management in Chessbase, you should be able to add it as an engine.
I just bought Rybka 3 Aquarium with the intention of using it with my chessbase, but now I am not sure if I can. Does anyone know if this is possible and, if so, how? Also, it looks like I can download a lot of stuff with the chessok downloader I got with Rybka. If I can't use Aquarium, can I download a version I can use with Chessbase?