Converting Perch Page to use Runway Master Page

Hi

I've followed these steps however have missed a critical aspect of the configuration as I keep getting Not Found errors when attempting to view my page in Runway https://docs.grabaperch.com/runway/getting-started/upgrading-perch-to-runway/

In Perch I had a page at /about/aboutus.php In runway I've copied this page to admin/templates/pages/aboutus.php (we use a root folder of admin rather than perch). The file now looks like this

<?php
include($_SERVER['DOCUMENT_ROOT'].'/includes/page_header.php'); 

perch_content('Page Body & Sidebar');


perch_pages_navigation(array(
        'from-path'            => '/about',
        'levels'               => 1,
        'hide-extensions'      => true,
        'hide-default-doc'     => false,
        'flat'                 => false,
        'template'             => 'sidebar.html',
        'include-parent'       => false,
        'skip-template'        => false,
        'siblings'             => false,
        'only-expand-selected' => false,
        'add-trailing-slash'   => false,
        'navgroup'             => false,
        'include-hidden'       => false,
    ));
?>

<?php
include($_SERVER['DOCUMENT_ROOT'].'/includes/page_footer.php');
?>

I've deleted the physical file now and have edited the page in Runway to use this aboutus.php page as the master page

The location path for the page is set to /about/aboutus

The Parent page is set to About

No URL pattern has been entered for the Routes (do I need to enter something here)

I have the following htaccess file at the root of the site (outside our admin folder)

# Perch Runway
RewriteEngine On
RewriteCond %{REQUEST_URI} !^/admin
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule .* /admin/core/runway/start.php [L]

When I try to access the page at mysite.com/about/aboutus I get the following error

Not Found

The requested URL /about/aboutus was not found on this server.

Can you advise what I've missed in the configuration?

Many thanks

Regards James