I'm hitting with an outbound transport failed in CCP. while adding the Vcenter, UCSM.
I have re-rechecked users credentials of the users I have created.
Please have a look on my issue screen shot:
What do you see in server logs? You might also want to consider contacting TAC, although I expect them to ask for the logs files as well.
Also verify that the authentication mechanism of the outbound agent matches the CPO web services authentication mechanism (Basic, NTLM, etc.)