This is one of the many things that have to be done for "Australian compliance"
US bikes and cars can have red rear indicators. Australian bikes (and cars) have to be amber.
Through the RAWS system this is just one of quite a few changes
UNLESS the bike is a private/personal import of a bike you have owned abroad for a period of time.
You still need amber indicators to pass the pits in any Australian state.
Depending on the model it is done in different ways. Some of the later bikes have no separate taillight brakelight all lights are in the indicators.
On my own "grey import" a 2008 CVO Softail , it had an LED stop/taillight as stock OEM and amber indicators , came from Texas so no dramas.
I imagine you are talking about a Breakout type setup ? What model is it you did not elaborate ?