Croatia finished third in Group B4, behind Wales and Ukraine, winning three of their six games.
They were beaten 4-0 and 3-0 by the Welsh and Oxtoby admitted that NI were in contact with Rhian Wilkinson’s side for information about Croatia ahead of the play-off.
“We got some inside information as football is a small place, but we know what to expect and we’ve planned accordingly, so it is about going out and executing our game plan and being consistent with that,” Oxtoby explained.
The Australian manager is without the likes of Joely Andrews, Kerry Beattie, Nadene Caldwell and Caragh Hamilton through injury.
She has also omitted former captain Marissa Callaghan and Demi Vance from the squad, leaving her with a youthful looking panel.
But Oxtoby believes that will work to her side’s advantage, alongside their experience of winning a Nations League promotion/relegation play-off against Montenegro earlier this year.
“The exciting part of this group is that they are quite young and they’re really keen, we have some experienced players in and around guiding them,” Oxtoby added.
“We have spoken about being in this situation with the Montenegro play-off, so we know what to expect and if we are consistent with our performance we will give ourselves a chance over two legs.”