The forest has an invalid replication authentication mode (msDS-replAuthenticationMode). It requires Kerberos mutual authentication, ...

The forest has an invalid replication authentication mode (msDS-replAuthenticationMode). It requires Kerberos mutual authentication, but the source server is either not joined to a domain, or is using a local service account. Replication with the source server will not be possible.

Please adjust the replication authentication mode on the source server before installing any replicas. Use repadmin /replAuthMode command. For more information about replication authentication mode, see "Replication and configuration sets" in the Active Directory Domain Services Administrator's Guide.