This guide is intended for multi-domain configuration running in a single Forest. As such, we assume that your LDAP is properly configured, users can login to the domain without issue and that the connectivity between the domains inside the forest is properly configured.
This type of Constrained Delegation is available only in domain controllers running in domain functional level 2012 or higher. Windows Server 2012 is the first to allow Resource Based Kerberos Constrained Delegation.
You need to have Global Catalog enabled and running.