Advantage Database Server
If your data files are located on a drive using NTFS, that PC's "system" group must have full access to the share which contains the data in order for the Advantage Database Server service to have access to that data. Note: It must be that PC's system group that has full access, not the domain's system group.
Advantage Database Server for Windows: The Advantage "rights checking" functionality is not fully supported with free connections. If Advantage "check rights" security is being used (the default is to check rights with free connections), and a user has READ access rights ONLY to a shared directory, Advantage will allow that user full read and write access to files in that directory. If the user does not have any access rights to the shared directory where the tables are located, Advantage rights checking functionality will work as expected.