Your standalone/config.js file appears to be missing. That file is required as it defines the URLs used to fetch the config and images.
If you are trying to use an external webserver, you will need to copy the plugins/dynmap/web/standalone folder to your web root. See the dynmap wiki for more information:
https://github.com/webbukkit/dynmap/wiki/External-Webserver-Basics
Please post in the discussion thread if you have further issues.