vtk data is not usable
The data on the vtk.org site is not usable by anything other than testing code. Please change it to have the same format as paraview. Basically, a human readable and usable data tarball, and a second tarball that installs in a hidden directory that is for the automatic testing codes. I would recommend calling the human readable VTKData, and the datasets for testing VTKTestingData.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information