When activating the Salesforce Securlet, you see the error "An Administrator from your organization must sign up for the CloudSOC service. Please contact your Administrator."
CloudSOC is looking for a Salesforce administrator that doesn't exist in the CloudSOC tenant.
Add the user as a SysAdmin in CloudSOC, and then activate the Salesforce Securlet using that user.
Salesforce Sysadmin's email address in Salesforce and CloudSOC must match
Note: You can find the user that was used by looking in Splunk with the Reference error.