Answered How to install an add-on that is not a transport package?

@nuan88, that's the build I made from the github archive. hhk222 was having difficulty getting the correct base path and URL for the _build configuration.

@hhk222, remember that a relative path like core/ is relative to the .php file being executed. Inside MODX, that's always the index.php file, so core/ would in fact be relative. But in this case you're running the whatever/_build/build.transport.php file, so core/ is definitely not relative to that. You would need something like ../../core/, or the absolute path from the server's file root. This is a path, not a URL.