Project Explorer is available to AEC Collection subscribers and Enterprise customers.
Project Explorer can be downloaded and installed in one of two ways:
Through
https://manage.autodesk.com
Products and Services
Architecture Engineering & Construction Collection
View Items
Through the Autodesk Desktop App.
Additionally, the free trial of Project Explorer can also be downloaded by navigating to the Project Explorer section on the Civil 3D product page and click 'Try it now'