Delphi: TOAuth2Authenticator with client_credentials - delphi

Question

A while ago I wrote a method in Delphi 2010 to get the OAuth2 token using the Indy components (TidHttp). See code below.
I am now doing something new in Delphi 10.4 and would like to use the REST components such as RESTClient, RESTRequest, TOAuth2Authenticator, etc.
Our grant type is Client Credentials but in none of the examples on the net could I find on how to use TOAuth2Authenticator with Client Credentials. Is it even possible?
We have a client id, client secret and token URL. We do not have authorization or redirect endpoints. In Insomnia, the setup will look like this:
Does somebody know how to get the token using TOAuth2Authenticator with grant type = client_credentials?
Here is the Delphi 2010 code:
procedure TfrmToken.btnGetTokenClick(Sender: TObject);
var
IdHTTP: TidHttp;
lsHttpError: string;
loRequest: TStringStream;
loRespJson: TMemoryStream;
liSuper: iSuperObject;
ldtExpiry: TDateTime;
begin
IdHTTP := TIdHTTP.Create();
loRespJson := TMemoryStream.Create();
try
IdHTTP.HandleRedirects := False;
loRequest := TStringStream.Create('grant_type=client_credentials&client_id=' +
edtKey.Text + '&client_secret='+edtSecret.Text);
try
IdHttp.IOHandler := TIdSSLIOHandlerSocketOpenSSL.Create(IdHttp);
IdHttp.Request.ContentType := 'application/x-www-form-urlencoded';
try
IdHTTP.Post(edtURL.Text, loRequest, loRespJson);
except
on E: EIdHTTPProtocolException do
begin
lsHttpError := E.ErrorMessage;
end;
on E: Exception do
begin
lsHttpError := E.Message;
end;
end;
if idHTTP.ResponseCode = 200 then
begin
liSuper := SO(StreamToString(loRespJSon));
edtToken.Text := liSuper.S['access_token'];
ldtExpiry := IncSecond(Now, liSuper.i['expires_in']);
edtExpiry.Text := 'Expires in ' + liSuper.S['expires_in'] +
' seconds. Time: ' +
FormatDateTime('yyyy/dd/mm hh:nn:ss', ldtExpiry);
end
else
begin
liSuper := SO(lsHttpError);
edtToken.Text := IdHTTP.ResponseText;
edtExpiry.Text := '';
end;
finally
FreeAndNil(loRequest);
end;
finally
FreeAndNil(IdHTTP);
FreeAndNil(loRespJson);
end;
end;