Shader error in 'Universal Render Pipeline/Terrain/Lit': maximum ps_5_0 sampler register index (16)

Hi xrdyne2, unfortunately this is a Unity limitation and not one imposed by Microsoft Mesh. The terrain material (and in turn shader) is using too many texture samplers. Some platforms can't sample more than 16 textures in a single shader. Note texture samplers != number of textures necessarily, but when authoring shaders this is often the case.

There are a few ways to fix this, you might be able to disable some of the rendering features on your terrain to strip out shader features and reduce texture utilization. Or, you can try using a different terrain shader, or author your own terrain shader.