I'm Australian, and I've never heard of Oula and can't imagine where it would come from.
Many, many names books/sites have a habit of calling anything they can't identify "Australian".
A few unusual combination names (such as
Narelle) have come out of Australia; other than that the only valid Australian names are Aboriginal names. There are at least 200 Aboriginal languages, and they of course have plenty of names which the speakers of those languages still use. However the only Aboriginal "names" on the web are place names (usually ones which have been used as suburbs, eg Jannali), plant names (Jarrah, Cardinia) or vocabulary words (
Kylie).
Please, please check your sources before labelling things "Australian"!
:-)