Confirmed that this is working now.
We are trying out the NopFeedManager for standard NopCommerce version 3.9.
Our hosting environment has two front facing web servers and a shared asset file server (/content/files is a virtual directory that points to a network share).
When attempting to create the feed for google, here is the error we get in the system log:
System.IO.DirectoryNotFoundException: Could not find a part of the path 'C:\nopcommerce\wwwroot\content\files\exportimport\google_en-us_7_temp84393594174893998677.xml'. at System.IO.__Error.WinIOError(Int32 errorCode, String maybeFullPath) at System.IO.FileStream.Init(String path, FileMode mode, FileAccess access, Int32 rights, Boolean useRights, FileShare share, Int32 bufferSize, FileOptions options, SECURITY_ATTRIBUTES secAttrs, String msgPath, Boolean bFromProxy, Boolean useLongPath, Boolean checkHost) at System.IO.FileStream..ctor(String path, FileMode mode, FileAccess access, FileShare share, Int32 bufferSize, FileOptions options, String msgPath, Boolean bFromProxy) at System.IO.FileStream..ctor(String path, FileMode mode) at FoxNetSoft.Plugin.Feed.Manager.Core.CustomFeedClient.GenerateFeed(FeedRec feed, IList`1& reportMessage) at FoxNetSoft.Plugin.Feed.Manager.Core.FeedManagerExport.ExportFeed(FeedRec feed, Boolean uploadFTP)
We aren't having any issues with resolving the virtual directory when it comes to uploading images (/content/images is also a virtual directory).