[ravintag]

Hi,
Hope this below information is of help to you.
Milestone monitor gets attached automatically when the event of the initiating agent satisfies there is no need to use the actions menu. (note you do not create milestone monitor, we create milestone template which inturn creates a monitor once a satisfying event is triggered) and in your case a milestone monitor will get created whenever an order base is created (if that is event condition).
An auto agent is used to perform a single activity or series of activities at given happening of an event whereas milestone monitor does proactive monitoring and performs various activites upon happenings of several satisfying events.