Our add-on uses the Lucene Query Syntax. As such, any filter criteria have to be built according to these rules.
In case you don't want to try it on your own, we published an article about possibilities for a birthday list as a techblog article: https://www.communardo.de/techblog/2014/07/15/birthdaylist-confluence/ Please be aware that this can only be used as a basis for developing your own macro, as it uses a slightly different date format and it was written for User Profiles for Confluence version 1.9.
Resources
Further examples how to create queries using Lucene query syntax (see section "Extended Search")
