My name is Silviu and I am a Technical Support Engineer (Tier II) at Okta. Seems we already have the "Oracle Hyperion EPM" Application added into our OIN. Please try to run a test with that one, linked to your custom Oracle domain. Note that it will have a banner saying "This integration was created by the community and hasn't been verified by Okta - contact Okta support if you run into any problems while setting up the app." Meaning we didn't actually guarantee the integration is working, so here might be the 'key' point. Still, as the community created it and tested, it might work successfully. For any further assistance please open up a case with Okta Support and get all the necessary pieces of information, if not provided yet.
Wish you all the best in your work!
Thank You, Silviu Muraru Technical Support Engineer | Okta Inc.