If they lied to you then you can return it. As a general rule I would not buy third party gear for, well, anything. As for it being compatible, you can most likely use it. There are programs out there that let you install and use Windows crap on OSX. Try downloading the drivers and see if there are Mac ones, the box could be wrong. As for Wiimote motion plus, unless you are using the features on the upgraded one it should not make a difference. What games do you want to play on there?
Arch
Intel Core i7 - 4510U
iHD4400
8GB RAM
Check here first:
wiki.dolphin-emu.org
Intel Core i7 - 4510U
iHD4400
8GB RAM
Check here first:
wiki.dolphin-emu.org