Link your Salesforce and Streamline accounts using the managed Streamline for Salesforce app to enable buttons and triggers without needing manual Named Credential or HTTP callout configuration. After logging in, Streamline automatically identifies and displays your connected organization(s) until you decide to disconnect from either Salesforce or Streamline’s user settings.

I suggest we wait until we add the button feature to post the portal card because the feature by itself will not bring any value to the user.