Hope you are doing well, as you are running an old version of passbolt, I guess you used the install scripts for your first install and then the documentation you linked to update a passbolt version install with the ubuntu package won’t work for you.
If you are sure that you installed passbolt with install scripts, you can use this documentation to upgrade from install scripts to ubuntu package, it will do the update and also ease the process for you to update your passbolt in the future Passbolt Help | Migrate passbolt CE from install scripts to Ubuntu package.
If you are unsure about your first install process, you can then execute this command :
dpkg -l passbolt-ce-server
You will either get this error saying that there is no package matching passbolt and then confirming you used the install scripts :
dpkg-query: no packages found matching passbolt-ce-server
In this case, you can use the link I provided you to upgrade passbolt CE from install scripts to Ubuntu package.
Or you will get information about the passbolt package you already installed, in this case just tell me and we will dig your issue together why your passbolt isn’t updating