You are running SENAITE 1.3.4.
SENAITE 2 has not been released in PyPi yet, so you have to define a statement in your buildout to use the source code from GitHub: 16. Write Your Own Add-Ons to Customize Plone — Plone Training 2020 documentation
Also, if you want to have full control of your code, you can have a look on how to setup the development environment in buidlout doc: Getting started with Buildout — Buildout 2.7 documentation