Because they're technically hard to implement, we currently support only a handful amount of extensions:
To use any of them, just add it from the app-store and refresh Gmail by double clicking on its icon. If it's still not working, restarting your Station should do the job.
If you don't find your extension, you can easily request it from within Station.
We’ll implement requests by popularity order every month & you’ll be notified with an in-app tooltip after each new release.