Thank you for reaching out to the Microsoft Q&A platform. Happy to answer your question.
If you are talking about the modernized appliance which is the new configuration server in ASR. In earlier version cspsconfigtool.exe was used to registering the configuration server to vault, to update the credentials for mobility agent installation, VMware host server creds etc.,
In the modernized appliance, you will use the appliance web page to update the credentials as shown in the below
For more details see, https://learn.microsoft.com/en-us/azure/site-recovery/deploy-vmware-azure-replication-appliance-modernized
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