When you run below,
docker run --runtime=nvidia -it -v /workspace/tlt/tlt-experiments:/workspace/tlt-experiments -p 8888:8888 -v /var/run/docker.sock:/var/run/docker.sock nvcr.io/nvidia/tlt-streamanalytics:v3.0-py3 /bin/bash
You already login the 3.0 docker.
You can directly run
# yolo_v3 train xxx