When historic anarchists like Malatesta critique democracy they mean representative democracy or systems of government based on majority rule. They don't mean systems of voluntary decision making based on each person in the group having a vote.

They in fact advocated and implemented such decision making systems. For example in Malatesta's pamphlet between peasants he writes that people will aim for "unanimity, and when this is impossible, one would vote and do what the majority wanted".

The difference between these systems of decision making and what they called democracy is that they are based on free association. If a minority doesn't like a majority decision they are free to leave or not participate in it.

Confusingly modern anarchists often now call these historic anarchist systems of decision making direct democracy. This represents a change in language but the ideas are the same.