@Shonnegowda SailPoint connector internally runs a single account aggregation post account creation, so please follow the below steps:
Step1: First make sure your single account aggregation is working fine. You are seeing ??? because the newly account created is not getting correlated to your account ID.
Step2: Make sure your response mapping is correct in create http operation. Assuming you are getting the username in response of account creation.
Following are two additional resources which you can go through as it really depends on the API response after account creation.
You may also look into below:
Create Account returns id(nativeIdentity in the schema), it is not getting mapped - Identity Security Cloud (ISC) / ISC Discussion and Questions - SailPoint Developer Community