Can you download the package again and do a directory compare with wwwroot copy (eg with WinMerge)
An example when this error can happen is
1. Casing of template tags has changed e.g.: <div><# SomeTag #></div> to <div><# sometag #></div>
2. Template tag is commented out <!-- <# SomeTag #> -->
Visual Studio will change the case of tags when copy/pasted or when you auto format "Ctrl+E, D" to lowercase in html files.
Result of this is that required control cannot be found and you get "Value must not be null for Controls and Behaviors".
You can also try rewriting all the files again from a fresh download.