Due to a limitation with redirects in the RA.Webservice REST it is not possible to natively trigger jobs through the REST API of SAP IBP.
See also here:
Instead of receiving the x-csrf-token and cookie a html body is received with the address of the SAML server.
The version of the REST interface integrated in the RA.REST cannot handle redirects to SAML
Release : 12.3
Component : AUTOMATION ENGINE
There are two possible workarounds: