An automatism is 'a combination, usually a passing move, which is repeatable and requires little-to-no thought to execute'.
For example, Conte's wall pass: When his teams are under pressure, the wingback will offer an easy pass, encouraging the press - because its easy to press a lone wingback - but the wingback plays a blind, round the corner pass over the top, which the forwards are attuned to, which can beat the offside trap if timed correctly. I recall Italy catching teams out with this, and that's when they had shite like Giacherrini and Pelle up front!
De Zerbi is more proactive, creating passing sequences to create faux-counter attacking situations.
I only really know of automatisms as passing sequences or pressing triggers / traps.