This is a Django tool, written with Django 1.11 for Python 2.7. If you have not installed that, please follow this guide or this guide if you are using windows.
Next, make sure that the pip package django-super-inlines is installed by running pip install django-super-inlines. Additionally, install django-grappelli. Note that this will install most liklely install a version that is (at least formally) incompatible with Django 1.11. This should not matter. Then run python manage.py runserver to test your installation. If you have a trouble with grappelli, try restarting your system or running the server once without grappeli by commenting out the lines grappelli and super_inlines.grappelli_integration from the INSTALLED_APPS list in GoodCompanyGameDesignDB/settings.py.
After changes to any models, run python manage.py makemigrations followed by python manage.py migrate to update the database. A migration is a transformation of a database from an old version of a schema to a new version. Creating the migration basically means that your changes to the models are translated into database transformations, running migrate is then the act of applying the transformations.