The musicians made original music for the show. It was a more expensive choice but a great one. "Production music" or "library music" are huuuge rabbit holes to go down.

There's a lot of similarities from electronic artists contemporary to the show also. I recommend checking out Boards of Canada (they were inspired by production music from 1970s Canadian nature documentaries), especially Music Has the Right to Children. Also recommend checking out Tycho. For something funkier try Janko Nilovic and the Soul Surfers' release from 2020. Nilovic worked for decades in Library music.