how to convert the soap receiver adapter user id and password into base64 encoding in SAP PI

Hi Experts,

My interface Asynchronous flow: SAP(Proxy) ------->PI-------->SOAP DellBoomi(Cloud Integration system).

from SOAP UI tool I am sending data successfully.

Please find the below SOAP Raw data from SOAP UI tool:

with same WSDL ,Target URL , userid and Password using in SAP PI 7.31.

while sending the data from PI to DellBoomi system ,I am getting below error.