Not able to integrate AEM and Adobe Campaign Standard via AEM cloud services

Hi Team,

I am trying to integrate my specific AEM instance with my Adobe Campaign Standard (ACS) sandbox by the recommended Adobe steps.

but While make connecting AEM cloud services with ACS server with "aemserver" user credentials , I am getting "incorrect credentials error" although they are correct.

Can you please tell is there any issue of firewall blocking ?

Or Do we need to white list the AEM server IP in the campaign standard instance?

Thanks!