What I did was (1) Start a new empty scene, then right after importing RWT into Unity (2) I just need to build my scene once to get a successful build even though the scene was empty. (3) Next, I used RWT to get the terrains and it worked without any error.

I'm not sure what happened but I think by building the scene in Unity, it will pull and set up all the plumbings needed to work with the external packages (in this case, it's RWT).

I tried to download a map area at the default location of RWT but I kept getting errors "Cant load elevation data
UnityEngine.Debug:LogError (object)". I tried both the ArcGIS (Esri) and Virtual Earth (Bing Map) providers, still no go.

My setup is a plain vanilla empty SampleScene with the followings:

O/S: Windows 10
Target Platform: Windows, Architecture: Intel 64-bit
Unity version 2021.3.3f1
RWT version Version 4.7.0.1 (2022.03.30)

No other third-party packages are installed.

Please Help. Thank you in advance!