To import the paper templates into Goodnotes and set them as Goodnotes-Template, you do not need to download the Goodnotes file, just download the PDF.
Instructions:
Open the Goodnotes App
Tap on the settings wheel
Manage Notebook Templates
You can now import the template into one of the categories or create a new category and import the templates into it.
More information: https://support.goodnotes.com/hc/en-us/articles/7353728093199-Add-external-templates-to-the-template-library