Is he/she authenticating with the correct credentials? Which OS? If it is Windows, can you check the ACL from the Security tab within the Properties of the share?
Can you check also unix permissions on the folder? You need to connect to your server via SSH, then (if for example the shared folder is named shared) go inside /var/lib/nethserver/ibay and check out the permissions for the main share. You should also be able to check full ACLs with getfacl.