Realtek - unlike common belief - is not producing audio controllers, but AC97 codecs. So in a nutshell - the manufacturer of your hardware makes the actual audio controller. In the example of a Realtek AC97 chip it is likely an onboard sound device.
Normally "sound blaster compatible" audio controllers do not need drivers, this is handled by the DOS game or app itself. You may need to set the BLASTER environment variable for some games.
Onboard sound devices are often NOT sound blaster compatible any more these days.
A notable exception would be the older VIA boards (VT82C686A/VT82C686B/VT8231) which came with a sound blaster emulation driver for DOS.
Some older BIOS also have options to enable sound blaster emulation for such embedded audio controllers. (Check your BIOS for these!)
I'd try to set the BLASTER variables and if that doesn't work check the drivers and documentation of the board manufacturer.