I have a simple scene where a volumetric like pass trough a ceiling and cast shadow on a wall and a floor. My problem is that the render in C4D look fine but in AE it look jaggy. My render is only black and white, I only use the render as a matte in AE.
You might also be looking at the unmatted RGB channel only in AE. Interpret the footage and set the matte to "straight" (if there is one). The matte will always be antialiased but the RGB footage may not be at the edges. C4D saves render time by letting the matte clean up the edges in 1 channel instead of using super sampling to do it in 3.