This iAWriter PDF template offers a corporate logo at the top right of each page, with a page count and GDPR document classification in the footer.
To modify the logo, open the template file and look under the Resources folder for the file logo.png. Note that the size of the image is specified in the header.html file, should you need to change the aspect ration.
The footer design is found in footer.html.
The overall document styling is set in the various CSS files, the main one being style.css.
You will need to ensure that in the Templates tab within Preferences that you have the Printing & PDF Export checkboxes ticked for Headers and Footers.
You can add the template using the Custom templates section in the same tab.