401 and Authentication failed

We have an okta service
when i post via postman it works great
when i try to post via visual studio app i’ve createdI get :
401 - Authentication failed because the remote party has closed the transport stream
in postman i have 3 headers:
Accept - application/json
Content-Type - application/json
Authorization - SSWS XXX…XXXX
how should i configure my http client in the app?