Retrieve the CA certificate also known as the root certificate from the certificate authority to upload into Universal ZTNA. For more information, see Windows Certificate Authority: Retrieve the CA (Root) Certificate.
Use this task to update or download certificates.
and select Update Certificate from the drop-down menu.

Note
After a successful validation and update of the CA certificate, active authentication sessions will continue to function. However, for all new connections, the handshake process will occur using the new CA certificate.
and select Download Certificate from the drop-down menu.