Having just setup the development environment myself, I think that this page may now be slightly out of date:
Specifically, the section that says:
You will need to checkout the external repositories to get everything, as not all components are stored in the main phpList repository.
Particularly the theme, “dressprow”
From what I can see, “dressprow” is included in the .gitmodules file, so, as advised at the top of the page, if you run:
git submodule init git submodule update
then it’s not necessary to also clone the dressprow project. In fact, if you do try you will receive an error:
fatal: destination path 'dressprow' already exists and is not an empty directory.
Hope that helps.