input directory validated against /cygwin//windows/systems32/log files is invalid because directory doesn't exist
Couple suggestions here:
1. Make sure the NiFi service user (user who owns the NiFi java processes) can access that directory path. If that user can not traverse that directory tree you will see this error.
2. Since you are using windows, try using the absolute directory path (C://cygwin//....)
Hope this helps,