'Engaging in the community' refers to viewing a page in the community, in the context of DAU/MAU.
MAU or Monthly Active Users is the #unique members (both logged-in and not logged-in) in a month. In Classic, we don't have a like-to-like metric representing the #unique members visiting community in a month. One way to compute this metric in LSI (Classic Analytics) is to use to the Unique Visitors metric in the 'Traffic' tab for a period of 30 days, after excluding the anonymous visitor count. Anonymous visitors can be excluded by applying the filter 'User Name ≠ Anonymous'.
