After POA 5.5 Update 1 installation or after POA upgrade from 5.4 to 5.5 File Manager returns this error for Windows websites:
There is no service to provide Web File Manager
During POA 5.5 Update 1 installation WinFileManager is replaced by WebFileManager. In some cases the replacement may not complete successfully and the new WebFileManager will not get installed.
To enable your customers to use File Manager on their IIS websites you need to install the WebFileManager (type: service) POA package on the IIS Web server.
See Windows Shared Hosting Deployment Guide for more details.