svea.js

const soap = require('soap');
const url = 'https://partnerweb.sveaekonomi.se/WebPayAdminService_Test/AdminService.svc?wsdl';

soap.createClient(url, (err, client) => {
  client.setSecurity(new soap.BasicAuthSecurity('finlandtest2', 'finlandtest2'))
  client.GetClientId({ SveaOrderId: 1075538 }, (err, result) => {
    console.log(err)
    console.log(result)
    console.log(client.lastRequest)
  })
});

svea_error.txt

{ GetClientIdResult:
   { ErrorMessage: 'An error has occured',
     ResultCode: '1000',
     ClientId: '0' } }

<soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:wsu="http://docs.oasis-open.org/wss/2004/01/oasis-200401-wss-wssecurity-utility-1.0.xsd" xmlns:tns="http://tempuri.org/" xmlns:msc="http://schemas.microsoft.com/ws/2005/12/wsdl/contract">
        <soap:Header>
        </soap:Header>
        <soap:Body>
            <GetClientId xmlns="http://tempuri.org/">
                <SveaOrderId>1075538</SveaOrderId>
            </GetClientId>
        </soap:Body>
</soap:Envelope>