Perhaps they meant beneath the center hub cap.
The BMW wheels (as been mentioned) will have the wheel's specs and 11 or 7 digit BMW part nbr either around the hub, below the hub cap, or on the rear of the spokes. I highly suggest looking up the BMW part nbr for the style 215 wheels you want. This wheel came on the e70 X5 & e71 X6. The X6 is an odd fitting in that the front & rear wheel hubs are different sizes...so if you are buying X6 wheels...you will need to buy wheel spacers for the front wheels to handle the larger (74.1mm) wheel hub. The e53 has a 72.56mm wheel hub.
If you go in to the purchased already armed with the correct information...you can save yourself a headache of not being able to mount them without extra hardware.
On my e38 that came with the basket weave Style 5 cross spokes...the BMW specs & part nbr was around the hub but hidden below the hub cap which has to be removed to see the wheel's specs:
On the BMW style 37 MPars...the BMW wheel specs & part nbrs were on the rear of the spokes:
Then sometimes the info is around the hub of the wheel if there's space and no hub cap...like the BMW Style 87 wheels from my e53 X5: