Question Custom Mesh UV mapping

I've been following along with Catlike Coding's hex map tutorial - as a guide for a similar terrain, so some code variance - and I'm having difficulty with texturing the procedural mesh. In the tutorial, we use vertex colours for a splat map along with a texture array so we can blend between different textures per tile. The shader code in the tutorial, however, is pre-URP, and so incompatible with my project; and I have next to no shader knowledge. I have made a texture array material in shader graph, which works fine on basic geometry, but appears stretched on the custom mesh. I am not entirely sure where I am going wrong so any guidance would be greatly appreciated.

Catlike Coding's Tutorial: https://catlikecoding.com/unity/tutorials/hex-map/part-14/

 

I should add that Catlike Coding does not seem to ever bother setting the UVs for the custom terrain mesh, yet his terrain is textured fine using his custom shader, which again, is not URP compatible.

 

To quote the tutorial itself:

In Shader Graph, the XYZ components are generally labelled as RGB.

 

Cheers, this helped me get it working.

For anyone who might like to see the graph:

 

If I could request your assistance again good sir; how can I select a colour for my texture based on the chosen index, which is stored in the UVs.

 

This configuration worked for me