Cant select faces on downloaded model

So, i downloaded this model from warenhouse Мартеновская улица, 41 | 3D Warehouse.
When I’m trying to edit it, selecting any face selects the whole model and there are no selectable lines on the edges. Using paint bucket on any part paints the whole model and trying to use extrude i get message about “can’t extrude softened or curved surfaces” though the model doesnt look curved of softened.

Unsoften the edges. If you look at the hidden geometry you’ll see those edges are shown to be softened. Select the entire lump of geometry by triple clicking on it and setting the Soften Edges slider to 20.