Hi @Rivindu_Bandara ,
This is a bit of a workaround, but if you know the Z/X/Y of the tiles you want to download, you can use Heron’s Import Vector Lite to import the PBF files served by the Mapbox Terrain vector tile service. Note that Import Vector Lite is available as part of v0.4.2-beta.1 in the Package Manager and works in a headless environment, but imports data raw without respecting Rhino’s units or EarthAnchorPoint, document attributes that aren’t available in a headless setup.
Let me know if you’d like me to develop the Lat/Lon to Z/X/Y tile functionality.
-Brian