The error message you're getting is "Connecting to remote server failed with the following error message : The WinRM client cannot process the request because the server name cannot be resolved. For more information, see the about_Remote_Troubleshooting Help topic"
This error is not coming from Identity Manager but is instead being returned by your endpoint.
This issue occurs if either an internal firewall or the Windows Remote Management service has not been started.
First confirm that host name resolution is working as expected. If it is not, please work with your network team to resolve this or if you have the access you can fix it by modifying the host files to include the IP/short name/FQDN of the machines. Your provisioning servers should have the info for your connector servers, AD endpoint and Exchange machine. Your connector servers should have the info for your provisioning servers, AD servers and Exchange machine. Your AD endpoint should have info for your provisioning servers, connector servers and Exchange machine, and finally your Exchange machine should have info for your AD endpoint, connector servers and provisioning servers.
If you're not having a DNS problem but you still see this error, something is off with your WinRM setup. WinRM needs to be installed and running on the CCS that you are using to connect to Exchange. If you have multiple CCS they all need WinRM. Plus WinRM needs to be installed and running on the endpoint.