The model is made in 3ds Max 2017. There are .max (2017 and 2014) and .obj files in the archive.
When importing the .obj file into the project you will see files with the name must_smooth _ ## on them you must superimpose the turbosmooth modifier to smooth the geometry.

Steps dimensions:
depth – 30 cm;
height – 15 cm;

Polygonazh (not including two additional balusters)
Polys: 449927
Verts: 408 190