Where you get historical data depends on where your catchment is. In general, you can get rainfall data from the Bureau of Meteorology and streamflow data from the water authority/department in charge of the area.
If you want rainfall data on a sub daily basis then you may need to pay a fee to get the rainfall data from the BoM, as for streamflow data, some state water departments provide streamflow data free of charge online but these are mainly located only on major rivers or tributaries. The local council might have their own rainfall or streamflow data but you would have to do your own research or contact them directly to find out.
When I run my model, I’m told there are some who are ya and to check the output file, which I think is RORBWin.tmp because it says “RORBWin Output File” at the top. In this file, there are many lines of text, but nothing is called an error unless it’s in the Code Nos.