Please check and make sure the privatekey is not missing for this certificate.
The setup is actually trying to run below command and its getting failed.
Enable-ExchangeCertificate -Thumbprint $thumbprint -Services SMTP
1.Open MMC and add the Certificate Snap-In for the Local Computer account.
2.Double-Click on the certificate that has thumbprint AC3215B73FDE0CD05713575010C9FD0435EA1678Note: In Windows Server 2008 it will be the certificate missing the golden key beside it.
3.Select the Details tab.
4.Click on the Serial Number field and copy that string.Note: You may use CTRL+C, but not right-click and copy.
5.Open up a command prompt session. (cmd.exe aka DOS Prompt)
6.Type: certutil -repairstore my “SerialNumber” (SerialNumber is that which was copied down in step 4.)
7.After running the above command, go back to the MMC and Right-Click Certificates and select Refresh (or hit F5 in the MMC)
8.Double-Click on the problem certificate. At the bottom of this window (General tab) it should state: “You have a private key that corresponds to this certificate.”
Now try to run the setup.