Unsupported Media error XML response

I'm trying to send a SOAP request to get XML data from a REST API. 

I tested the request on SOAP UI and also with PHP and it is working. The API needs a token and customer key to get a response from the API. When I do it on Power Query I get this error:

DataSource.Error: Web.Contents failed to get contents from 'https://service4.ultipro.com/services/EmployeePerson' (415): Unsupported Media Type
Details:
    DataSourceKind=Web
    DataSourcePath=https://service4.ultipro.com/services/EmployeePerson
    Url=https://service4.ultipro.com/services/EmployeePerson

I think is something with the syntax. This is my code for the request:

let
    Source = Xml.Tables(Web.Contents("https://service4.ultipro.com/services/EmployeePerson"
    ,[Content=Text.ToBinary("<s:Envelope xmlns:a='http://www.w3.org/2005/08/addressing' xmlns:s='http://www.w3.org/2003/05/soap-envelope'>
  <s:Header>
  <a:Action s:mustUnderstand='1'>http://www.ultipro.com/services/employeeperson/IEmployeePerson/FindPeople</a:Action> 
  <UltiProToken xmlns='http://www.ultimatesoftware.com/foundation/authentication/ultiprotoken'>6fsdfdsfsdf54acdsfsdfdsfsdf6</UltiProToken> 
  <ClientAccessKey xmlns='http://www.ultimatesoftware.com/foundation/authentication/clientaccesskey"&Character.FromNumber(34)&">ABCDE</ClientAccessKey> 
  </s:Header>
  <s:Body>
  <FindPeople xmlns='http://www.ultipro.com/services/employeeperson'>
  <query xmlns:b='http://www.ultipro.com/contracts' xmlns:i='http://www.w3.org/2001/XMLSchema-instance'>
  <b:EmployeeNumber /> 
  <b:FirstName> 
  <b:FormerName /> 
  <b:FullOrPartTime /> 
  <b:Job /> 
  <b:LastHire /> 
  <b:LastName /> 
  <b:Location /> 
  <b:OriginalHire /> 
  <b:PageNumber /> 
  <b:PageSize /> 
  <b:PayGroup /> 
  <b:SupervisorLastName /> 
  <b:TerminationDate /> 
  <b:TimeClockId /> 
  </query>
  </FindPeople>
  </s:Body>
  </s:Envelope>"),Headers=[#"Accept-Encoding"="gzip,deflate", #"Accept"="Basic fsdfdsfdsfdsMjAxNyE=", #"Content-Type"="text/xml;charset=UTF-8"]]
)),
    Table1 = Source{1}[Table],
    Table0 = Table1{0}[Table],
    Table2 = Table0{0}[Table],
    Table3 = Table2{0}[Table],
    Table4 = Table3{0}[Table],
    Table5 = Table4{1}[Table],
    Table6 = Table5{0}[Table],
    #"Changed Type" = Table.TransformColumnTypes(Table6,{{"CompanyCode", type text}, {"EmployeeNumber", Int64.Type}, {"FirstName", type text}, {"LastName", type text}})
in
    #"Changed Type"

I tried switching text/xml to application/xml and got same error.

According to this website: https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/415

The error is hapenning because the server refuses to accept the request because the payload format is in an unsupported format.

But I already have a header for xml. Maybe I have to code this differently because the request to the service needs to include a token and customer key?

Or https://service4.ultipro.com/services/EmployeePerson is not compatible with power query?

Thank you in advance