open3D - How to project an image (texture) onto a 3D mesh

I am new to open3D and working on a process to automatically create mesh's of various terrains and apply generated maps on those terrains. I have been using open3D to view the meshes, but I'm not sure how to project my png onto that mesh.

Code

import open3d as o3d
import open3d.visualization.rendering as rendering

material = rendering.MaterialRecord()
material.shader = 'defaultUnlit'
material.albedo_img = o3d.io.read_image('terrain_image.png')

mesh = o3d.io.read_triangle_mesh("terrain_mesh_file.stl")
mesh = mesh.compute_vertex_normals()
o3d.visualization.draw({'name': 'terrain', 'geometry': mesh, 'material': material})

This is showing the mesh, but the image does not seem to mapped onto it in any way:

Here are the files I am working with

Mesh Image

Alternatively, if I use one of the primitive meshes I'm able to successfully map the image onto the mesh.

material = rendering.MaterialRecord()
material.shader = 'defaultUnlit'
material.albedo_img = o3d.io.read_image('terrain_image.png')

box = o3d.geometry.TriangleMesh.create_box(create_uv_map=True)
o3d.visualization.draw({'name': 'box', 'geometry': box, 'material': material})

This almost certainly has something to do with the uv_mapping which I do not fully understand yet. I get that it is a mapping of 0,1 to translate my image onto the mesh, but I dont understand how I would construct one in this scenario.