Ok, I see. That one is from a version so old that it wasn’t possible to work without creating sets and surfaces manually yet and only the .unv meshes could be imported (no step files) 
So if you watch Matej’s channel, be careful about the versions and possibly choose new videos as this channel shows the progress of the development across the years.
You can find more recent basic tutorial here: https://www.youtube.com/watch?v=XMNVtqrb3is
Since PrePoMax is actively developed, some things changed since then (especially meshing) but most stuff should be up-to-date.