I need a way to give a sql authenticated user read access to a windows directory
One thing you could try is to create stored procedure that would select from a View
When creating stored procedure, use EXECUTE AS clause and set it to a Windows-authenticated account (grant all necessary permissions to this account, required to read from I:\Folder)
Grant execute on procedure to SBA_USER
This way when SBA_USER  executes procedure, procedure does select from View, from behalf of the Windows-authenticated account