Without more details on the markings, it's going to be hard to identify. 15x6 was a common OEM size in the 90's. But, unless the wheel is stamped with that size, it's possible the seller just laid a ruler across the barrel and called it 6" wide.
It's definitely not the BBS wheel from the 90-92 VW GTI 16V. With the recessed wheel bolts, it's possible it's not a BBS wheel at all.