I have a quick question that you all might be able to help me with
Does GOG Galaxy client make all games purchased on GOG able to play multiplayer like Steam?
I bought Act of War hoping to play it with my buddy and can not find a way to do so over the internet

Only games that support the GOG Galaxy multiplayer use the Galaxy multiplayer, just like Steam games do need to support Steam multiplayer in order to use it.
According to GOG, the GOG version of Act of War has no working GOG Galaxy nor third party multiplayer.