Hi @hhdhhd I'm afraid there is no direct solution for you. I see that you are running Cinema 4D R21, which implies Python 2.7.7.
Looking at the issue Cryptodome developers seem to have messed up Python2 import statement with Python 3 import statement. So the only way is to fix their module for Python 2.7.X.
Slight note their module is working nicely with the latest Cinema 4D R23 which uses Python 3.7.7.