So because there is not too much information about the offline maps for the node-red-contrib-web-worldmap node...
By following this post, I was only able to configure the executable file, and map file, but I am stuck as I do not know what to do next...
Any help and experience with 'worldmap' is acceptable 
Not really a Node-RED question - I used mapserver so had to create the required tile index files from the tiles I had using gdaltindex Tile Indexes — MapServer 7.6.2 documentation - that creates the .shp and dbx files used by the map file etc. Where you get you georeferenced map tiles (usually large geotiffs) from is down to you.
There are probably other tiling map servers now available but I haven't used them so can't comment.
Copyright OpenJS Foundation and Node-RED contributors. All rights reserved. The OpenJS Foundation has registered trademarks and uses trademarks. For a list of trademarks of the OpenJS Foundation, please see our Trademark Policy and Trademark List. Trademarks and logos not indicated on the list of OpenJS Foundation trademarks are trademarks™ or registered® trademarks of their respective holders. Use of them does not imply any affiliation with or endorsement by them.
The OpenJS Foundation | Terms of Use | Privacy Policy | OpenJS Foundation Bylaws | Trademark Policy | Trademark List | Cookie Policy