Yes, and your PCMCIA-USB comes with drivers that install a raw USB driver in the system (because Windows 95 certainly didn't have USB support on board, it was an addition to the Win95 OEM SR2 that was rather unstandardized). Raw USB is just that, raw. many different USB devices have many different requirements and therefore there exist many different USB device classes, such as mass storage devices, human interface devices, still image capture, printers, serial communication devices etc. Each of them has a different protocol on top of the USB bus and therefore needs different drivers to allow Windows or any OS to do something with them.
Your PCMCIA driver CD likely will install a USB mass storage device driver that makes such devices available to Windows as volumes. It most likely also comes with a human interface device driver, that allows mice and keyboards to be recognized by Windows. It may not come with an USB communication device driver, which would be needed to make a USB COMM class device appear as an additional RS-232 port in your computer. And it will most likely not come with more specialized drivers such as still image class devices or printers or network devices.
All that said it will be very difficult nowadays to find a PCMCIA-USB interface and even more difficult to find one that still supports Windows 98 or even worse Windows 95 since Windows 95 had no USB support in any of its standard releases.