After installation you get this message about - Font "Arial" does not support style "Regular".

This message tells you that you are missing that Font style. It's likely that it is corrupt or a windows update somehow removed it. That can happen when uninnstalling software
Solution
To fix this issue, please go to "Start", rightclick and choose "Run"

Then type c:\windows\fonts\arial.ttf

This dialog will appear and you click "Install"

When the installation is finsihed, please start your Revit with Naviate and the error message is now gone.