OSM AU Map - No Map Data Available

Hi All,
I found this website as I am looking for a free map for my vacation in Australia.

I downloaded the selected au map img file and uploded it to garmin internal memory Map folder.

But I seem to encounter a huge problem, with the img file.

With the IMG file, I can find the city or search points of interest.

But I cannot search for addresses. Why I try with only the OSM map enabled, it says No Map Data Available. If I enable my base map, I can find cities in that country but not in Australia. Also cannot change the country to Australia. No option to do so.

Anyone can help.

How to force Garmn to search for Australia addresses.

My Garmin is a nuvi 1490.

Please help.