Most client workstations log in when they are started. This login process establishes an authenticated connection to eDirectory and a licensed connection to the network server to which you are attached. A licensed connection gives your application rights, such as rights to a particular file system volume, to perform eDirectory operations.
If your application is meant to run on a client workstation, you can either assume that a licensed connection has been established, or you can log in to establish a licensed connection. In either case, your development burden has been greatly reduced.
The authentication problem that you will most likely encounter is the need to establish a second connection to another server. For example, your program might read a File object and discover that it refers to the file system of a server to which you have not established a licensed connection.
To gain access to another server, your application can open another connection using NWDSOpenConnToNDSServer and then authenticate the connection using NWDSAuthenticateConn.
NWDSAuthenticateConn authenticates and licenses the connection so that you can access the file system.