You are trying to add VMware Cloud Director 10.4 to Aria Automation 8.18 as a cloud account and you hit the below error talking about a invalid certificate
Failed to validate credentials. Error: javax.net.ssl.SSLHandshakeException: SSLHandshakeException invoking https://hostname.example/api/sessions: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target, SSLHandshakeException invoking https://hostname.example/api/sessions: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target, PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target, PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target, unable to find valid certification path to requested target
VMware Cloud Director 10.4
Aria Automation 8.18
To communicate with other servers securely, the Aria Automation server must be able to verify their identity. For this purpose, you need to import the TLS certificate of the remote entity to the Aria Automation trust store.
Refer Create a VMware Cloud Director cloud account in VMware Aria Automation for steps to configure