Reading here, you have to turn on the plugin globally as well as locally

https://alienvault.bloomfire.com/posts/661002-plugins-management

Pays to read all the documentation!

To get there, configuration, deployment, click the tiny icon system detail on your alienvault center (to the very right magnify glass thingy)

Then click Sensor Configuration. Click Collection.

Search for sonicwall and then add it.

Yay, I see events coming in!