Some more info and pictures on this weapon can be found in "Tot in de verste uithoeken", a book on the Dutch East Indies local Gouvernementsmarine or Colonial Navy.
There are several pictures of which this one is the best. It does not only show two guns, but it also gives some impression from the rear/above.
The same book also shows a picture of one of the five Landing Craft Infantry employed, fitted with an AAC 3,7cm as well! In another publication (on Dutch Marines in Java) I saw a pic of what seems to be an LST with an AAC in one of the front AA gun positions.