After you create a unique domain, you will need to assign it to a partner. Partners cannot just pick a unique domain from their ad resource center.
From the left navigation bar, select Content → Unique Domains.
Find the unique domain you want to assign to a partner.
Under Actions, select [Drop-down menu] → Send to Media.
Next to Media Partner, select which partner you want to assign a unique domain to.
Next to Unique Domain, select which unique domain you want to use.
Next to Deal, assign a deal to the unique domain.
Next to Comments, add any comments or instructions for your partner.
Next to Email Address, if you want to send the unique domain to your partner using an email that is not their default, enter it here.