I'm trying to play this on a 98/DOS machine and I can't configure sound. The game runs and the intro video sound works fine, but in-game is completely mute. Any other game also works fine.

Note that in the included image I show Duke 1.5 setup as an example. All 5 "sound card type" options work. These options are SB 1.0, 2.0, Pro, Pro 2, and 16/AWE. Eradicator setup only shows 16/AWE as the driver option and only the ability to change the address. I'm not sure if I'm doing something wrong or if this game is just fickle.

If you hit up arrow on the sound card selection it will show many more options. Just keep hitting it and more show up.
And, yeah, skipping the auto setup only offers the address. Which I assume it queries for the rest of the info?
Note: Eradicator may use the CD for redbook CD music in game. Without the "CD" there may not be music on a W98 computer if you just move the files over, as DOSBox mounts the CD image as a CD when this is run on modern systems.

Make sure your BLASTER env variable is set correctly?
Usually the SB drivers setup set this kind of thing up for you though (both in Windows DOS Prompt and quitting to full DOS which uses an autoexec.bat oddly named something like .DOS).

If you really want to change things up manually, there is the DIG.INI file in the ERAD directory.
IRQ and the two DMA's are set to "-1" which means auto detect. Can just set them to the actual values if you so wish and should work. You can also change the name and driver there. Though I would use the setsound to change those values if possible. DEVICE is probably just the same name as in SETSOUND. Driver is one of the "name".dig files. SB16.DIG or SBPRO.DIG. And many more.