You need to set up certificates for the Horizon FLEX server so the certificates can be used to authenticate the Horizon FLEX virtual machines.

You must configure the IIS SSL server certificate for the Horizon FLEX server to ensure secure communication between the Horizon FLEX client and the Horizon FLEX server. The IIS SSL server certificate ensures that certificate authentication can proceed in the Horizon FLEX virtual machine.

VMware recommends that you use a certificate issued by a certificate authority (CA), such as Entrust or Go Daddy, or a trusted third-party certificate, on your Horizon FLEX server. If you are using a self-signed certificate or a certificate from an internal CA instead of a generally trusted certificate, you should take steps to ensure that the certificate is trusted on all end-user computers that will download and use Horizon FLEX virtual machines.