Samba fails to add a user entry, how do I fix this?

You need to create a UNIX user named student before you create a samba user named student.

Maybe you did not create it yet. So to add it for the first time to samba need to add the

-a

option

sudo smbpasswd -a test

A samba user is setted and added in a different way than unix users. That means that not because a unix user exists, a samba user exists. The way to add a samba user is setting its password from unix user