u/Similar-Ad-6438

Hey guys, so I tried basically everything while importing a 3d city model but no matter what file type I used (dxf, ifc, stl) The geometry is always weird and full of these smaller lines.
The only format that seems to work is .obj but when importing an obj, I cant delete any of the building and when I convert it to a Morph it ends up looking like this again.
Any help on this matter would be much apreciated.
Note: Site used for 3d model download: topo export