The default configuration contains a 'Visits Over Time' widget, usually what we look at are DAU, WAU & MAU. Can you put these very basic features into the default configuration? If can't, can anyone give advice how to achieve it?
By "Active users" do you mean "Unique visitors"? We process the value of Unique Visitors, but you may need to enable it to get the metric for all periods: https://piwik.org/faq/how-to/faq_113/
The Unique Visitors is currently available in a few widgets but not on its own, it will show up with the other sparklines. I think we have an issue where we discuss we would create one widget for each metric in the app, but can't find it now.