I needed to allow MKCOL in the http_methods. I got that in Firefox, click inspect, then go to network, tell it to show Method. That's the method that wasn't being allowed.
Now, if only I knew what method the app on my phone uses.
The http_methods you need in DirectAdmin are below:
The app doesn't say method not allowed anymore. I found those here. Well, not all of them. But the ones I was missing.