Angular 6 SAML authentication with OKTA

We have developed an angular application for our frontend and which connects to backend API in TIBCO.

Frontend angular needs to be authenticated with OKTA using SAML, subsequently the SAML token coming from OKTA to angular frontend should be passed as header to TIBCO API to complete the authentication part of the application. Can you please help here how to do SAML authentication with OKTA using angular