@keydi, since HA is running, I connected from a client to http://[IP-address]:8123 and installed the HA Community Ad-on “SSH & Web Terminal”: Home Assistant Community Add-on: SSH & Web Terminal. From there you can work on OS level.
Installation is straightforward. Just keep in mind that you need to assign a password in the configuration section of the add-on.
If you assign a user too, you can connect with putty as well.