Hi Austin,
It looks like the issue you're facing is probably due to a mismatch between the location of your connection and the managed API. Your connection is set to "Australia East," but the managed API seems to be in a different region, which is why you're getting that error.
To fix it, start by checking the region where the managed API is deployed. It needs to be the same as the region of your connection. If the API isn't in "Australia East," you'll need to create a new connection in the correct region. Another option is to modify the resource group's location to match the API's region, if that's an option for you.
Here another issues related to fortigate and playbooks:
- https://learn.microsoft.com/en-us/answers/questions/823996/playbook-for-ip-blocking-using-fortigate-firewall
- https://github.com/Azure/Azure-Sentinel/issues/4767
If the information helped address your question, please Accept the answer.
Luis