I had this problem.
Thanks to the SSSD guessing the realm, you can set your ldap_user_principal to the following, and it will append the @realm.
ldap_user_principal = sAMAccountName
Also, IMO, ignore the suggestions in that link, use the AD provider. Ditch the bind account.
id_provider = ad
auth_provider = ad
chpass_provider = ad
access_provider = ad
Use msktutil to join the pc to the AD domain, or create the krb5.keytab file on your domain controller and move it to the pc running fedora, if you do that, be sure to tell selinux to accept the foreign file.
Chris