On the Domain Ownership page, select Copy to clipboard to copy the domain proof token information for the domains you've ...

On the Domain Ownership page, select Copy to clipboard to copy the domain proof token information for the domains you've selected to include in the hybrid deployment. Open a text editor such as Notepad and paste the token information for these domains. Before continuing, use this information to create a TXT record for each domain in your public DNS host. Refer to your DNS host's Help for information about how to add a TXT record to your DNS zone.