You'll need DOS drivers. Furthermore, not all such PCMCIA adapters can use all types of PCMCIA cards. As it has a VIA chipset and not the Ricoh chipset that's recommended, it may only support network adapters (LAN, Wifi) and the like, and not other types of PCMCIA cards.

Furthermore, the PCMCIA card reader does not include any storage itself, for that you need PCMCIA cards that support storage devices, such as CF card adapters, microdrives, etc. The maximum capacity depends on the PCMCIA card you use, and they too need DOS drivers (unless the system can boot from PCMCIA and the card supports it).