The module will use the Octopus URL set on the environment variable $Env:OctopusURL You can set this variable manually or using Set-OctopusConnectionInfo

As for the authentication, you can use the following methods:

Using an API Key

If you don't have an API Key, you can create one from the Web UI or using New-OctopusAPIKey (super recommended)

When using this method, the module will use the API Key set on the environment variable $Env:OctopusAPIKey. You can set this variable manually or using Set-OctopusConnectionInfo

If you want to know the API Key and Octopus URL set on your current session, use Get-OctopusConnectionInfo

Setting credentials for future Powershell sessions

If you want to set the credentials for all your Powershell sessions, the best way would be to include one of the following lines on your Powershell Profile

Set-OctopusConnectionInfo -URL [Your Octopus URL] -APIKey [Your API Key]

or

$env:OctopusURL = [Your Octopus URL]
$env:OctopusAPIKey = [Your Octopus API Key]