I know this is quite old, but the response did not answer the question.
I have a similar question.
Script modules don’t help, as they allow you to enter/save/share script snippets directly into Octopus.
They are not relevant to try to use the functions in existing powershell modules (that are not directly pasted into Octopus)
The OP was asking how to reference the functions published in a Nuget package.
I’m trying to understand how to reference the functions in third-party Powershell modules that are installed on the Octopus server.
How does one make powershell modules available from script steps?