This is continuing from this documentation: https://aussieguy92.com/wiki/unity-101/how-to-create-and-apply-a-basic-coloured-material/
Once you have created material and applied it to an object to create a default shader you can tweak the base map where we previously set the colour to red to apply a texture to the overall object. You can drag a texture image to the box next to the ‘Base map’ option to wrap a texture around the object.
In Unity 2019 it was easy to drag a material to an object and apply it, but in Unity 2020 you must drag the textures and assign them to the shader manually. This can be done by dropping and dragging the textures into your maps. This process is the same for applying metallic maps, normal maps, height maps etc.