numpy can't read the sample training data (.npz)

I got this error when running DeepCell:
`IOError: Failed to interpret file './train_data/HeLa_all_61x61.npz' as a pickle`
I tried a few other training data sets provide in this repository and got the same error.
Is this a problem with the data set, or numpy version incompatibility? What numpy version was used to create the sample train data sets (.npz)?