in the 80s and early 90s, there were three (well, more than three, but three competitive) types of computers on the market: your typical macs and intel machines, along with something called an atari. due to issues that exist in reality (such as price), the atari machines became standard amongst diy electronic musicians in the late 80s and early 90s. the computers used by bands like autechre, ministry, skinny puppy, kmfdm, etc for sample editing and sequencing were mostly ataris, using software written for atari.
probably the most well known software atari daw was cubase, which enjoyed a run as a popular windows/mac daw in the 90s before being dismantled by, i think, yamaha, in the 00s. the vst interface was not developed until 1996, but it was built on top of previous technology.
all that to say that there were probably "plugins" used on the album, but you'd need an atari emulator to actually use them.
another piece of relevant history: one of autechre's contemporaries, rdj, aka the aphex twin, almost single-handedly popularized software synthesizers. if you'd like to hear some early vst plugs, the aphex twin is a better place to look than autechre.
if you really want to capture the spirit of this type of 90s techno, though, you'd better learn to program in C. a lot of these artists programmed their own software. for a (not so) gentle introduction to this approach to music, i'd try a program called MAX.
young people that are interested in seeing some old (but very modern) computer software running in real-time (it's an early version of pro tools) can also consult the 'gave up' video by nin, 1992: watch?v=yVpw1SwJRBI.
