I think you have to take off the foam disk. The foam disk is meant to be a polisher in and of itself.
My buffer has a hard rubber circular piece attached to it onto which I put the bonnet.
2004 E60 530is, Delivered 12/12/03, TiSilver/LGrey, PP, SP,PS, PDC, ACC, FRS, Step, Xenons, clear bra, body colored rear inserts. (Retired, 1983 henna red 320is)
2004 Corvette Z06 Commemorative Edition