AI is a touchy subject, seeing as it's such a wide field there's no "right or wrong" way to do it, just ways of a varying efficiencies - In theory the bare minimum would be to add an action to the end of the unit creation functions to cause them to 'attack move' to the enemy's base/s - But naturally that would presume you have only one or two lanes all leading to the same spot (ultimately) and I they have no side passages to take into account. You may also find the odd unit stops abruptly and does nothing (you could tidy them up with a periodic selection trigger).
In short, we can't really tell you how to make your AoS AI - We'd need a much better idea of what your map is like and what the AI is meant to be capable of - In fact it'd probably be much easier for someone to just code the map's AI for you but finding someone to do that would be a bit problematic me thinks.