The only thing I found in regards to Medium being a 3d app of some kind is this: https://www.oculus.com/medium/ is that what you’re using? I would need to see some screenshots of what your models look like. Usually textures need to be imported separately and manually into Unity. Importing the model just imports the mesh, materials will usually get created along with it but you’ll need to usually assign the texture maps manually.
Blender, Zbrush and the like are just 3d programs. Blender being the most versatile since it can do a lot, while Zbrush is specifically for sculpting high resolution models. If Medium works for you then great, I would take a look at the FAQ for their software and see how you could export the textures applied to your 3d models.
