@Jason M Thank you for reaching out to us on Microsoft Q&A platform. Happy to assist!
Based on the information provided, I understand that you are trying to update the change/update the credentials in the ASR appliance to connect to the vCenter.
The ASR Configuration Manager appliance should be working on localhost, you are probably in the wrong server. Do you have any ASR services running/installed?
In the latest versions web portal is removed, cspsconfig tool can be found from Program files(x86)\Microsofot Azure SiteRecovery\home\svsystems\bin\cspsconfigtool -
Hope this helps. Please reply if you need further assistance!