System authentication method is configured to use LDAP.
There is a group with the 'GUI Access: Internal' flag configured, but it is not used for creating this user.

Normal user creation (administration -> users)

• No Password field is shown (which is correct because LDAP is used.
• All required fields are filled (except the non-existant password field ofcourse)
  User creation fails with the error "ERROR: Password should not be empty"
  Apparently, the default password 'zabbix' when non-internal auth is used, is not set.

A small note on the side (minor issue, if at all)
When, in the above situation, i add the described group, with the 'GUI Access: Internal' flag on, i still get no password fields.
If this is done for an existing user, the password change button is shown, because of this group.
This is separate from the main issue, but it would be nice (if possible) to fix this.