Naviate Infrastructure 2019.1 is now available for Civil 3D 2019.
Please note that Naviate for Civil 3D 2019 requires the AutoCAD 2019.0.1 Update, which resolves an issue with AutoCAD crashing when loading a CUIx-file from an external application. You can find the update in Autodesk Desktop App. You can also download it here: https://knowledge.autodesk.com/support/autocad/learn-explore/caas/sfdcarticles/sfdcarticles/Update-2019-0-1-available-for-AutoCAD-and-AutoCAD-LT.html
Please, contact us if you have any questions.