I'm trying to setup the SAML configuration in my instance. I'm using a 3rd party as identity provider and the test customer community user has already been setup manually and should be a customer community portal user. When I attempt to login as the customer I'm receiving the following error message: 
 
/SamlError?ErrorCode=5&ErrorDescription=Unable+to+create+user&ErrorDetails=Should+not+be+a+portal+user"
 
Does anyone have any additional details about the portal user piece specifically?