Materials can provide exposure to authentic input through the advice they give the instructions for their activities and the spoken and written texts they include.
They can also stimulate exposure to authentic input through the activities they suggest (e.g. interviewing the teacher, doing a project in the local community, listening to the radio etc.) In order to facilitate acquisition the input must be comprehensible (i.e. understandable enough to achieve the purpose for responding to it). Means that there is no point in using long extracts from newspapers with beginners but it does not mean that beginners cannot be exposed to authentic input.
They can follow instructions intended to elicit physical responses, they can listen to stories, they can listen to songs, they can fill in forms.