Patch management for a closed network not working

Hi,

I have Desktop Central 10 installed in a closed network with no access to the Internet and have followed the steps here:
https://www.manageengine.com/products/desktop-central/help/configuring_desktop_central/patch_management_for_closed_network.html.

When I try to update the Patch Database in Desktop Central using the "Update Now" button, it warns me that I need a connection to the Internet.

I click Continue as I've set the proxy settings to "No Internet Connection" already, but there's an error stating "Patch Sync Failed! Unable to download - http://patchdb.manageengine.com/dc-crs/crs-meta-data.xml".

How do I get Desktop Central to import the patch database I've placed in the CRSData directory?

Thanks