We're glad you liked the game!
All sounds we used are listed in spreadsheet on the bottom of the itch.io page. The music you probably are referring to was uploaded on freesound with CC0 license - 2 years before "I am on observation duty 2" released. So I guess Notovia may also found it the same way we did.
https://freesound.org/people/Magmi.Soundtracks/sounds/417993