Importing assets from sketch up to unity 3d

After i import the building in unity 3d it lost all his textures and worst it get a strange reflective light like red or something like that pls help…

Personally I would export to a .FBX file type, this imports into unity with a materials folder too. Also when exporting be sure to check what direction the faces are pointing (in or out) as if this is incorrect and you don’t render double sided faces it can cause transparent walls.