the credentials you use when to make the connection from a remote computer must be exactly the credentials needed to see those same files (as if you logged in directly). The computer holding the files will be verifying them against its accounts.
If you can see a folder, but not the files inside, what are the permissions? you need at least valid READ permissions to see inside a Folder. The files themselves must have valid read permissions to see their sizes, and valid read/write permissions to change them.
Remember that you must be checking these from the Remote computer to get the permissions seen from there, which may not be the same as the permissions provided to a local Admin User..