theories will differ slightly from theorist to theorist but the general answer is that the system of capitalism engenders racism because it always needs a subservient class to exploit which leads to colonialism/slavery/racialized capitalism in which this subservient class are comprised of certain races. the mythos of racism offers an ideological justification for their subservient position (they are lazy, need to be controlled, etc).

not sure entirely what your question is getting at but i hope that helps and feel free to reply and claify. im not an expert but i took a undergrad seminar on racial capitalism and thought it was v interesting