Can I convert a rim brake wheel to a disc brake wheel?
The hub for a disc brake wheel has the mounting for the brake rotor machined into the left side, and has shorter spokes that side to make room for the brake. 

If the eBay wheels are for rim brakes, they won’t have these disc mount features out the box. If the spoke counts match and are sufficient, you could theoretically rebuild the rims onto disc specific hubs, but at best you would only be able to reuse half the spokes, quite possibly you’d need to replace the hubs and all the spokes.  

It’s not that this can’t be done, but it would probably be less economical in time and money than paying return postage or fees for listing the wheels again on eBay yourself to then buy the right set. You would also have to sell the unwanted hubs and spokes to recover the money sunk into those. It would certainly be more hassle!

Great point from @Rider_X that disc wheels can require higher spoke counts, so that may take the whole exercise off the table anyway. Rim version of these wheels are 20 spoke front, 24 spoke rear, while the disc version is 24 front, 24 rear. In general terms, not having enough spokes on the disc (or any) wheel would be a bad idea.