Set up the CRS (Coordinate Reference System) and the geolocation of your project.

Geolocation Concepts:

Setting Geolocation for a construction project :

Useful link to find the EPSG number required for your project : https://epsg.org/home.html

Note also that the geolocation folder has been moved to the optional content (video not updated) : C:\\Program Files\\Dassault Systemes\\B423_Cloud_Content\\win_b64\\resources\\geolocation
You can install the optional content from the cloud by clicking on the small arrow close to the Civil 3D app launcher in the web browser.

Importing a geolocated dwg inside 3DX (before 21x FD07). Workflow is identical after 21x FD07 (that is why I leave this more complete video here), but the geolocation has been automated (no more need to copy/paste Northing/Easting Coordinates):