Turning off cycle paths

We ride on left here in Australia, so I was riding down the left of the cycle path, wanting to turn. I slowed and I put my arm out to indicate I was turning, then a peleton of cyclists overtook me on the right.

They got angry with me because I was turning. I am a new cyclists to this and don't know what I did wrong

What is the courtesy here, on the road I wouldn't overtake a car turning on the side they are turning especially if they were indicating they were turning that way, what's the ettqutte here is cycling different?. I didn't even know they were there, if I had just turned there would have been a big crash.

edit. it was at a intersection where the path went two ways they went straight ahead and I went right. I wasn't even just turning off at some random point

Edit 2. These replies are very concerning that they treat a new cyclist who just asks a question so rudely I had heard that cycling is a very non welcoming sport but i didn't expect this