@ManikandanMo
I hope should refer to the Adobe Official documentation, if you working to setup the commerce-integration-starter-kit.
https://developer.adobe.com/commerce/extensibility/starter-kit/integration/create-integration/
Additionally verify
- All required API services should be enabled in the connected project workspace
- "EVENT_PREFIX" should have a value the .env file
- OAUTH_CLIENT_xxx credentials in the .env file
Let me know, if it works!