This installation method doesn’t install a supervisor. It is just for installing HA Core in Docker.
to install the full HA Supervised installation you will need to re-install using the correct script. You can’t install the supervisor later after you have already installed it this way.
Also the name is not Hassio. It’s Home Assistant. There are several ways to install it. two of those ways gives you the supervisor. Those are HA Supervised and HA OS.
You will have to decide which way you want to install it and then follow the instructions for those methods.
HA OS instructions can be found on the main HA site under “Getting Started”.
The other method instructions are in the community guide wiki post for that method.