This is not specific to meshlab, but may help since it illustrates that the model you downloaded just needs some finessing to get the texture to display in the software you are using. Am sorry I havnt used Meshlab in a few years so have forgotten how to do this there.
So the .mtl files are not really needed unless you want the diffuse(albedo), transparency and other shader data… which you wouldnt get from a 3d scan anyway. The texture coordinates / uv data will be stored in the .obj itself.
heres an example from Malopolska’s account
I downloaded this scan. Like you said it comes with just the obj and the textures.
and sure enough when you import it into a program like Blender, all you see is a default albedo grey…
What you need to do is tell your program to use the texture map for the diffuse/albedo slot.
In blender you do this by first adding a material…
then set the base material to an image texture
and now you have a slot you can load the texture into
just navigate to the folder with the image file and load it here
in this case Malopolska has provided both a low resolution as well as a high resolution(I think 4k) file, use whichever one you need.
once loaded… you wont see any change on the model in blender…
because we are not in the right viewport mode… so switch that to one of the last two modes