I just tried installing OABot locally, and didn't have a zotero_cache_key.txt yet.
The code (settings.py) contains a helpful message:
ZOTERO_CACHE_API_KEY = open('zotero_cache_key.txt','r').read().strip() if not ZOTERO_CACHE_API_KEY: raise ValueError('Please provide a Zotero cache API key '+ '(email dev @ dissem . in to get one.)')
But the ValueError isn't presented because Python errors ("No such file or directory") trying to open the file first.