I believe you will just need to use the full UNC path to the network drive rather than using a mapped drive. So instead of using something like "D:\datasource.xlsx" you would want to use "\\serverName\folderName\datasource.xlsx"
Hope this helps!
its giving error of insufficient privileges.
You need to find the service ID that Tableau Server is running as and give that ID the appropriate permissions to access the appropriate files and folders on the network location of your files.