Copper thickness as stated in the email is 1.6mm. I set that too, for both bottom and top layer. So 62.9 * 2 mil + 47.244 + 6.693*2 = 186.43. If you add in the gnd and vcc plane thickness, it adds upto 189. The email didn't state anything about the thickness of the gnd/vcc plane (and Gold Phoenix isn't being helpful now) so I left it as default.