I am using getDatabaseByName method of API REST from ARIS Repository API as Consumer on IS.
I have a token from umc, this works.
I’ve done a request in postman and it works rightly setting the umcsession param as apikey auth
Have you checked all the other configuration settings match your postman request?
I notice postman is sending 1 header and your IS request is not.
There are also configuration of basePath, params/path and httpMethod. etc.
The configuration of your auth document seems to be correct for the APIKEY method.
Is there a way to capture the request generated by restClient in a debug log somewhere for you to be able to compare to the postman request?