For anyone interested, here's some details:
The HTTP method implemented by the service is: http://<SAPserver>:8000/sap/opu/odata/EHSMM01/LWM_SAFETY_OBSERVAT
When you configure the app, you need to set this up as your backend endpoint. You can also set this up as your HTTP authentication for your security profile.
You don't need to use the Gateway Management Cockpit. Just create an application with app ID:
com.sap.bsuite.erp.ehsm.safetyobserver
and use the above information for the backend and security profiles.
That's all!