Hi @bsudabathula
There can be two major issues here.
1) Downloading WSDL file using MC credentials only: (This step is missed frequently)
This very important step you need to download WSDL files using Message Center credentials given by the support team.
Use below URLs to download WSDL:
Session Token: https://<server>/nl/jsp/schemawsdl.jsp?schema=xtk:session
RT Event: https://<server>/nl/jsp/schemawsdl.jsp?schema=nms:rtEvent
Note: Please replace server name as your instance URL
Once you will hit these URLs on the browser adobe will prompt to enter username password. Use MC credentials only shared by the support team.
2) Always use MC user credentials to generate session token and use the same in rtEvent WSDL's push event method
Your application server public IP from where you are calling Adobe Campaign Message Center API should be whitelisted. (Although this is not the reason for Invalid Login Password error). You will get 403 forbidden error and Response Null if IP not whitelisted.