OK then, the red and white RCA plugs are analog audio outputs for the right and left channels of a stereo signal. No center channel. Both will require an amplifier.
Fot a center channel you might be able to use that "digital" RCA output if, in fact, that is what it is.
You'll need to feed it to a home theatre receiver with a HT processor to derive the signals and send them to individual amps, which are included in the receiver. Then you will have the full compliment of channels, including a aubwoofer, to choose from, including the center only.
Given my druthers, I'd go for a stereo setup with two speakers and a small amp/receiver if $$ is an object.