How do I build the package?

Since this project was created using the Quickly, you can just run 'quickly package' or 'quickly package --extras' in command line to create an installable debian package.

I tried that, but I got

ERROR: Python module helpers not found
ERROR: Python module parcel_trackerconfig not found
ERROR: Python module Builder not found
ERROR: Python module Window not found

However, "quick run" did work. I think I'm going to stick to that, since it's all I need for testing.

That errors can just be ignored, they are not affect the building process. If it fails, you should look for the error in some other place.
However, the 'quickly run' is sufficient, you are right.

Umm the whole error message is

----------------------------------
Command returned some ERRORS:
----------------------------------
ERROR: Python module helpers not found
ERROR: Python module parcel_trackerconfig not found
ERROR: Python module Builder not found
ERROR: Python module Window not found
----------------------------------
An error has occurred when creating debian packaging
ERROR: can't create or update ubuntu package
ERROR: package command failed
Aborting

It looks like this bug: https://bugs.launchpad.net/python-distutils-extra/+bug/746565
but I can't reproduce it, so it might be something else. Any ideas?

You should probably run quickly with --verbose or --debug key (I do not remember exactly).
However I suppose the packaging fails because you have Quickly version without my last fixes that are already merged to trunk, but not included into packages yet.