What is Materialism?
Materialism is simply the claim that all we observe- the universe and everything in it- can be explained/ accounted for by matter, energy and what emerges from differing interactions of matter and energy.
Materialists are people who adhere to that doctrine.
However information is neither matter nor energy so materialists claim it emerges from the aforementioned interactions.
Of course all of that is, to date, untestable and therefor beyond the realm of science.