No, I think if you’re using the nextcloud all in one image, then the management image connects to the docker socket and deploys nextcloud using that. The you could be able to update nextcloud via the web ui.
https://github.com/nextcloud/all-in-one?tab=readme-ov-file#how-to-update-the-containers
So I don’t know how much you know about the shell, but the way that the linux command line works is that there are a set of variables, called environment variables, which dictate so me behavior of the shell. For example, $PATH variable, refers to what directories to search through, when you try to execute a program in your shell.
The documentation you linked, wants you to create a custom shell variable, called SCALE_PATH, consisting of a folder path, which contains the compiled binaries/programs of scale you want to run.
This command:
export PATH="${SCALE_PATH}/bin:$PATH"
temporarily edits your PATH variable to add that folder with the scale programs you want to run to your path, enabling you to execute them from your shell.