Process Flow Azure Service Bus Auth Configuration

We are trying to set up a process flow outbound message to go to an Azure Service Bus.

I am struggling a bit with the authentication setup. The two options are to use a SAS key or a Subscription key.

I would prefer to avoid using a SAS key if possible, as it looks like these have to be programmatically generated for Service Bus, which I don’t believe Alliance is capable of doing. Also, they expire.

My preference then would be to use the subscription key, but I’m not confident in exactly what that is referring to. I tried using the primary key from the Shared Access Policy, but I get a 401.

The process flow documentation doesn’t go into any detail here.

Is anyone able to assist?