The following files need to be placed in the folder:
- Sitecore.Client.dll
- Sitecore.Kernel.dll
- Sitecore.Logging.dll
- Sitecore.Update.dll
- Sitecore.Zip.dll
These files should be from a 8.x solution.
Current testing based on Sitecore 8.0 rev. 141212 (8.0 RTM).