Hi,
I just installed that webpart and the main reason why it's not working is because 'LoadTransformation' is moved from CMSDataProperties into TransformationHelper in k11. I imported web part (followed instructions from blog that you shared here) and on line 212, you should change this:
br.ItemTemplate = CMSDataProperties.LoadTransformation(this, Transformation);
with
br.ItemTemplate = TransformationHelper.LoadTransformation(this, Transformation);
After that, rebuild solution, solve errors in console(in my case I had some problems with CustomResponseRepeater.ascx.designer.cs, but I solved in the way that I created new clean .ascx control and then just copied code from imported custom webpart).
You can also find proper package for kentico 11 in this post, called 'v11.0.10'.
Best regards,
Dragoljub