After a while following the documentation, I was able to reproduce the error, trying to find more information about the case I have seen that in GitHub repository there is an open issue in which it is said that this theme is not compatible with Eucalyptus.
If your instance is not very old you are using Ficus which is the current version, if the previous version (Eucalyptus) is not compatible with this theme, I'm afraid Ficus will not be either.
In any case, could you confirm it with the developers of the theme? Possibly they can give you a better solution.
Carlos R. Hernández