401 Unauthorized out file while using proc HTTP to access the sharepoint

[learn_SAS_23]

options set=SSLREQCERT="allow";

/* for use on Windows and Unix workspace servers */
%let _metauser = %scan(%sysget(METAUSER),1,'@');
/* for use on MVS, Stored Process, and Pooled Workspace servers */
/* %let _metauser = %scan(%sysfunc(getoption(METAUSER)),1,'@'); */
data ids;
  length name $ 16 purpose $ 40;
  label name="Value Name" purpose="Purpose";
  infile datalines dsd;
  input name purpose;
datalines;
SYSUSERID, SAS session host account
_CLIENTUSERID, Windows user ID in SAS EG
_CLIENTUSERNAME, Windows user name in SAS EG
_METAUSER, SAS metadata user ID
run;
proc sql;
  select t1.name,
    t2.value,
    t1.purpose
   from work.ids t1
   inner join sashelp.vmacro t2 on (t1.name = t2.name);
quit;

filename hdrs "/home/headers_sharepoint.txt";
filename Testing "/home/out_sharepoint.txt";
%let Test_URL = "http://spappfarm.intra.net/iapps/SAR/_api/web/lists/GetByTitle('test')/items";
proc http
    url = &Test_URL.
    out = Testing
    method = "get"
	headerout=hdrs
	webusername="S123456"
webpassword="testpassword!!"
webauthdomain="test"
auth_negotiate;
run;



data _null_;
   infile Testing;
   input;
   put _infile_;
run;

data _null_;
   infile hdrs;
   input;
   put _infile_;
run;

%put HTTP Status code = &SYS_PROCHTTP_STATUS_CODE. : &SYS_PROCHTTP_STATUS_PHRASE.; 

Hello Team, 

i am trying to execute above proc HTTP code, to access the sharepoint URL to read the lists from it. for some reason am getting the 401 Unauthorized out file .  

1. which  user from below box , proc HTTP is using for authentication.

2. what will be fix for this ?

Value Name	Macro Variable Value	Purpose
_CLIENTUSERID	'S123456'	Windows user ID in SAS EG
_CLIENTUSERNAME	'my name'	Windows user name in SAS EG
_METAUSER	S123456	SAS metadata user ID
SYSUSERID	S123456	SAS session host account

Here is the out file : 

HTTP/1.1 401 Unauthorized
Content-Type: text/plain; charset=utf-8
Server: Microsoft-IIS/8.5
SPRequestGuid: 6f3e11a0-f343-5019-a75a-65092f2b13f2
request-id: 6f3e11a0-f343-5019-a75a-65092f2b13f2
X-FRAME-OPTIONS: SAMEORIGIN
SPRequestDuration: 2
SPIisLatency: 0
WWW-Authenticate: Negotiate
WWW-Authenticate: NTLM
X-Powered-By: ASP.NET
MicrosoftSharePointTeamServices: 15.0.0.4885
X-Content-Type-Options: nosniff
X-MS-InvokeApp: 1; RequireReadOnly
Date: Tue, 28 Dec 2021 15:48:01 GMT
Content-Length: 16

[Ksharp]

calling @ChrisHemedinger