How to display Tile Layers in a AGOL Webmap properly

[SarahInglis3]

I am trying to add png rasters as a tile layer into a webmap in ArcGIS Online. I am adding the png raster tile images from this website Free 4G | Spark NZ . I have added the tiles but not proving as simple as just adding the tiles like in the image below. I'm looking for some more guidance here how I can get the image to display properly. Is this a projection issue. Do I need to do some processing first to get it into a format that will display as a tile layer? I've tried setting the Tile Coverage but that didn't change anything.