Dag Ron,
IMO it may be easier to post a picture of the text.
Without looking at the actual foto as well as the actual text, my first impression is that, according to my translation (allowing for mistranscription in the text provided), the picture shows a paramount chieftain accompanied by his retinue who had arrived to celebrate the birthday of her/his majesty the queen/king of Holland on 31 Aug 1920?
Groetjes uit Down-Under (Australie)