“net use z: \\macserver\sharename /persistent:yes”
Make that into a .bat file and put in the “netlogon” share of your DC. Open Active Directory Users and Computers, find the user account, go to the “Profile” tab, set the logon script to the name of the .bat file.
Next time the windows users logon, they will have a mapped drive to the mac server. What filesystem is the Mac share using? HFS only has read support for windows, so it needs to be NTFS or something else “windows compatible”.