No /opt/redash folder when installing through docker?

I am new to installing and using Redash and i went through the official docs and followed the redash installation using Docker https://redash.io/help/open-source/dev-guide/docker but i did not get an /opt/redash directory, I am on Ubuntu 20.04.

Any help will be appreciated. Thank you.

yes , there will have /app in docker container.
Why do you need /opt/redash?