Hi Tung,

Unfortunately the files are not backwards compatible and there are some new geometry types that are only available in Rhino 6.

Would it be possible for you to upgrade to Rhino 6? Rhino offers an evaluation version that is valid for 90 days. https://www.rhino3d.com/download/rhino-for-windows/6/evaluation

If this is not a possibility, you can follow along using Rhino 5, the models I use are very simple and not absolutely necessary.

Best,

Arie